The Go Blog

Go maps in action.

Andrew Gerrand 6 February 2013

Introduction

One of the most useful data structures in computer science is the hash table. Many hash table implementations exist with varying properties, but in general they offer fast lookups, adds, and deletes. Go provides a built-in map type that implements a hash table.

Declaration and initialization

A Go map type looks like this:

where KeyType may be any type that is comparable (more on this later), and ValueType may be any type at all, including another map!

This variable m is a map of string keys to int values:

Map types are reference types, like pointers or slices, and so the value of m above is nil ; it doesn’t point to an initialized map. A nil map behaves like an empty map when reading, but attempts to write to a nil map will cause a runtime panic; don’t do that. To initialize a map, use the built in make function:

The make function allocates and initializes a hash map data structure and returns a map value that points to it. The specifics of that data structure are an implementation detail of the runtime and are not specified by the language itself. In this article we will focus on the use of maps, not their implementation.

Working with maps

Go provides a familiar syntax for working with maps. This statement sets the key "route" to the value 66 :

This statement retrieves the value stored under the key "route" and assigns it to a new variable i:

If the requested key doesn’t exist, we get the value type’s zero value . In this case the value type is int , so the zero value is 0 :

The built in len function returns on the number of items in a map:

The built in delete function removes an entry from the map:

The delete function doesn’t return anything, and will do nothing if the specified key doesn’t exist.

A two-value assignment tests for the existence of a key:

In this statement, the first value ( i ) is assigned the value stored under the key "route" . If that key doesn’t exist, i is the value type’s zero value ( 0 ). The second value ( ok ) is a bool that is true if the key exists in the map, and false if not.

To test for a key without retrieving the value, use an underscore in place of the first value:

To iterate over the contents of a map, use the range keyword:

To initialize a map with some data, use a map literal:

The same syntax may be used to initialize an empty map, which is functionally identical to using the make function:

Exploiting zero values

It can be convenient that a map retrieval yields a zero value when the key is not present.

For instance, a map of boolean values can be used as a set-like data structure (recall that the zero value for the boolean type is false). This example traverses a linked list of Nodes and prints their values. It uses a map of Node pointers to detect cycles in the list.

The expression visited[n] is true if n has been visited, or false if n is not present. There’s no need to use the two-value form to test for the presence of n in the map; the zero value default does it for us.

Another instance of helpful zero values is a map of slices. Appending to a nil slice just allocates a new slice, so it’s a one-liner to append a value to a map of slices; there’s no need to check if the key exists. In the following example, the slice people is populated with Person values. Each Person has a Name and a slice of Likes. The example creates a map to associate each like with a slice of people that like it.

To print a list of people who like cheese:

To print the number of people who like bacon:

Note that since both range and len treat a nil slice as a zero-length slice, these last two examples will work even if nobody likes cheese or bacon (however unlikely that may be).

As mentioned earlier, map keys may be of any type that is comparable. The language spec defines this precisely, but in short, comparable types are boolean, numeric, string, pointer, channel, and interface types, and structs or arrays that contain only those types. Notably absent from the list are slices, maps, and functions; these types cannot be compared using == , and may not be used as map keys.

It’s obvious that strings, ints, and other basic types should be available as map keys, but perhaps unexpected are struct keys. Struct can be used to key data by multiple dimensions. For example, this map of maps could be used to tally web page hits by country:

This is map of string to (map of string to int ). Each key of the outer map is the path to a web page with its own inner map. Each inner map key is a two-letter country code. This expression retrieves the number of times an Australian has loaded the documentation page:

Unfortunately, this approach becomes unwieldy when adding data, as for any given outer key you must check if the inner map exists, and create it if needed:

On the other hand, a design that uses a single map with a struct key does away with all that complexity:

When a Vietnamese person visits the home page, incrementing (and possibly creating) the appropriate counter is a one-liner:

And it’s similarly straightforward to see how many Swiss people have read the spec:

Concurrency

Maps are not safe for concurrent use : it’s not defined what happens when you read and write to them simultaneously. If you need to read from and write to a map from concurrently executing goroutines, the accesses must be mediated by some kind of synchronization mechanism. One common way to protect maps is with sync.RWMutex .

This statement declares a counter variable that is an anonymous struct containing a map and an embedded sync.RWMutex .

To read from the counter, take the read lock:

To write to the counter, take the write lock:

Iteration order

When iterating over a map with a range loop, the iteration order is not specified and is not guaranteed to be the same from one iteration to the next. If you require a stable iteration order you must maintain a separate data structure that specifies that order. This example uses a separate sorted slice of keys to print a map[int]string in key order:

Maps explained: create, add, get, delete

Go maps are implemented by hash tables and have efficient add, get and delete operations.

assign to map golang

Create a new map

Add, update, get and delete keys/values, for-each range loop, performance and implementation.

  • A map (or dictionary) is an unordered collection of key-value pairs, where each key is  unique .
  • You create a new map with a make statement or a map literal .
  • The default zero value of a map is nil . A nil map is equivalent to an empty map except that elements can’t be added .
  • The len function returns the size of a map, which is the number of key-value pairs.
Warning: If you try to add an element to an uninitialized map you get the mysterious run-time error Assignment to entry in nil map .
  • When you index a map you get two return values; the second one (which is optional) is a boolean that indicates if the key exists.
  • If the key doesn’t exist, the first value will be the default zero value .
  • Iteration order is not specified and may vary from iteration to iteration.
  • If an entry that has not yet been reached is removed during iteration, the corresponding iteration value will not be produced.
  • If an entry is created during iteration, that entry may or may not be produced during the iteration.
Starting with Go 1.12 , the fmt package prints maps in key-sorted order to ease testing.
  • Maps are backed by hash tables .
  • Add, get and delete operations run in constant expected time. The time complexity for the add operation is amortized .
  • The comparison operators == and != must be defined for the key type.

Go step by step

assign to map golang

Core Go concepts: interfaces , structs , slices , maps , for loops , switch statements , packages .

Learn Python practically and Get Certified .

Popular Tutorials

Popular examples, reference materials, learn python interactively, go introduction.

  • Golang Getting Started
  • Go Variables
  • Go Data Types
  • Go Print Output
  • Go Take Input
  • Go comments
  • Go Operators
  • Go Type Casting

Go Flow Control

  • Go Boolean Expression
  • Go if...else
  • Go for Loop
  • Go while Loop
  • Go break and continue

Go Data Structures

  • Go Functions
  • Go Variable Scope
  • Go Recursion
  • Go Anonymous Function
  • Go Packages

Go Pointers & Interface

  • Go Pointers
  • Go Pointers and Functions
  • Go Pointers to Struct
  • Go Interface
  • Go Empty Interface
  • Go Type Assertions

Go Additional Topics

  • Go defer, panic, and recover

Go Tutorials

Go Pointers to Structs

In Go, the map data structure stores elements in key/value pairs . Here, keys are unique identifiers that are associated with each value on a map.

Create a map in Golang

The syntax to create a Go map is:

This code creates a map named subjectMarks. Here,

  • [string] - indicates that keys of the map are of string type
  • float32 - indicates that values of the map are of float type
  • {Golang", "Java", "Python"} - keys of the map
  • {85, 80, 81} - values of the map

Example: Map in Golang

Here, we have created a map and printed the key-values of a map.

Note: We can also create a map using var keyword. For example,

  • Access Values of a Map in Golang

We can access the value of a map by using the corresponding key. For example,

Here, we have used expressions

  • flowerColor["Sunflower"] to access the value of the key Sunflower
  • flowerColor["Hibiscus"] to access the value of the key Hibiscus
  • Change value of a map in Golang

To change the value of a map, we can directly assign a new value to the corresponding key. For example,

In the above example, we have changed the value of a map by re-assigning the key "US" with a new value "Washington DC"

  • Add Element of Go Map Element

So far, we have created a map with a predefined set of elements. However, we can also add elements to a map.

To add an element, we can assign a new value along with a new key. For example,

Here, the code

  • students[3] = "Robin" - adds a new element with key 3 and value Robin
  • students[5] = "Julie" - adds a new element with key 5 and value Julie
  • Delete Element of Go Map Element

To delete an element of the map, we can use the delete() function. For example,

Here, we have used the delete() function to remove the element denoted by the key "John" .

The function takes two arguments:

  • personAge - name of the map
  • John - key of the element which is to be deleted

Note: If the key passed to the delete() function is not present inside the map, the function does nothing.

  • Looping through the map in Golang

We can use a Go for range loop to iterate through each element of the map. For example,

In the above code, the for range loop accesses each key/value pair of the map.

Working of the for range loop

Note: We have used the Printf() function to make our output look much cleaner and understandable.

Frequently Asked Questions

Till now, we have provided the initial values while creating a map. However, if we need to create a map without any initial value, we can use the make() function.

Once we create a map with the make() function, we can now perform all other operations (change, delete, access) to the map.

We can also use the for range to only access the keys of a map. For example,

Notice the use of the for range loop,

Here, the second entity (capital) is not used because we only want to retrieve the keys "Nepal" , "US" , "Norway" of the map.

We use the blank identifier _ with the for range loop to access the values of a map. For example,

Notice that we have used _ in place of the country (for keys). This is because if we have to use every variable that we declare inside the body of the for loop.

So, if we have used country (variable to denote keys), then we must use that inside the loop. Otherwise, we will get an error.

Table of Contents

  • Introduction
  • Map in Golang

Sorry about that.

Related Tutorials

Programming

Go by Example : Maps

Next example: Range .

by Mark McGranaghan and Eli Bendersky | source | license

  • PyQt5 ebook
  • Tkinter ebook
  • SQLite Python
  • wxPython ebook
  • Windows API ebook
  • Java Swing ebook
  • Java games ebook
  • MySQL Java ebook

last modified August 24, 2023

Go map tutorial shows how to work with maps in Golang.

A map is an unordered collection of key/value pairs, where each key is unique. Maps are also called dictionaries, associative arrays, or hash tables. The size of the map (the number of key-value pairs) is determined with the len function.

Maps are created with make function or with map literals.

To remove a pair, we can use the built-in delete function. The default zero value of a map is nil .

We use Go version 1.18.

Go map init

The make function creates an empty map.

We have a map of Benelux states.

A map of string keys and string values is declared.

With the make function, we create an empty map.

We add three pairs to the map.

We can shorten the syntax by using the := operator.

Go map literal

To create and initialze a map with literal notation, we specify the key/value pairs inside the curly {} brackets. Keys and values are separated with a colon character. Each pair is separated with a comma.

In the code example, we create a map of constants using map literal syntax.

Go map size

The size of the map is determined with the len function. It returns the number of pairs in the map.

In the code example, we create a map of countries, where the country codes are keys and the country names are values. We print the number of countries in the map.

There are four key/value pairs in the map.

Go map loop

With for and range keywords, we can loop over map elements.

In the code example, we loop over countries map in two ways.

In the first case, we loop by pair objects.

In the second case, we loop by keys and values.

Go map check element

We check if a value exists by referring to its key. If we have one variable on the left side, we either get an existing value or a zero value. If there are two variables on the left side, we get the value and a boolean value indicating the existence of the key in the map.

In the code example, we check the grades of students.

Here we print the grade of Lucia.

Since Peter is not in the map, we get a zero value (0 for integer).

Here we get the grades and the boolean values as well.

This is a concise syntax for getting the boolean value and checking it in the if statement.

Go map remove element

An element is removed from a map with the delete function.

In the code example, we remove one country from a map of countries.

Russia was successfully removed.

Go map is a reference type

Go map is a reference type. It means that when we assign a reference to a new variable or pass a map to a function, the reference to the map is copied.

Modifying countries2 map, which is a reference to the countries , the original map is modified as well.

Go map of structs

In the following example, we work with a map of structs. A struct is a user-defined type that contains a collection of fields. It is used to group related data to form a single unit.

In the code example, we have a map of users. Each user is represented by a Go struct.

In this article we have worked with map in Golang.

My name is Jan Bodnar and I am a passionate programmer with many years of programming experience. I have been writing programming articles since 2007. So far, I have written over 1400 articles and 8 e-books. I have over eight years of experience in teaching programming.

List all Go tutorials .

Maps in Golang

Maps are one of the most useful data structures. It can store in key-value pairs and doesn’t allow for duplicate keys. Now, we will learn how the Go programming language implements maps.

What is a map?

A map is a key-value pair storage container. It offers fast and efficient lookups. And it doesn’t allow duplicate keys while it can have duplicate values.

Declaration of a Map in Go

Now we will see how to declare a map in Go.

In the above example, the key is of type int while the values are of string type.

Initializing a Map

Let’s see how we can initialize a map with values.

1. Using make() function

The function make(), can be used to initialize a map as shown below.

2. Using literal syntax

Maps can be initialized using map literal syntax. Below is an example illustrating that. Let’s take the same code before and modify that to initialize with map literal.

Working with maps in Golang

We can insert, delete, retrieve keys in a map. Let’s see how to do that.

1. Inserting elements in a map

You can insert keys in two ways. Either insert keys when initializing or use index syntax to initialize.

2. Getting values from a map

We can get values associated with keys from a map using index notation as shown below.

3. Check if a key exists

We get a boolean when we try retrieving a value. That helps to check if a key exists.

4. Delete key from a map

We use the delete function to remove a key from a map. Let’s see an example of how it is done.

5. Iterating over a map entries

Using range we can iterate over a map and get keys and values both.

This is how we can add or remove items, retrieve keys and values from a map. It is one of the most useful data structures.

MarketSplash

How To Use Golang Make Map Effectively

Explore the practical aspects of utilizing the make function in Golang for map creation and management. This guide provides clear examples, error handling techniques, and real-world scenarios for effectively working with maps in Go, ensuring you can handle data collections with confidence.

In the world of Go programming, working with maps is fundamental for storing and managing collections of data efficiently. Understanding the make function is crucial as it initializes a new map, setting the stage for robust data handling. This knowledge allows for more organized and efficient code, enabling programmers to manage data collections with ease and confidence.

💡 KEY INSIGHTS

  • The make function in Go is essential for initializing maps, combining memory allocation and initialization for immediate use.
  • Providing an initial capacity during map creation optimizes memory usage and performance, especially for large data sets.
  • Maps in Go offer flexibility with various data types for keys and values, enhancing the adaptability of data structures.
  • Effective error handling in map operations, such as checking for key existence, is crucial for robust and reliable Go applications.

assign to map golang

Understanding The Make Function

Creating a map with make, setting and retrieving values, handling errors with make map, practical examples of make map, frequently asked questions.

In the Go programming language, the make function is a built-in utility primarily used to initialize slices, channels, and maps. Unlike the new function, which only allocates memory, make does both allocation and initialization. This distinction ensures that the data structure is ready for use immediately after its declaration.

Syntax Of Make For Maps

Practical usage.

The general syntax for using the make function with maps is:

For instance:

When working with maps, it's often beneficial to provide an initial capacity. This can optimize memory usage and performance, especially when the expected number of entries is known beforehand.

In Go, creating a map involves both allocation and initialization, and the make function is the tool for this job. It's essential to understand the correct way to use make to ensure that your maps work as expected and are efficient in terms of memory and performance.

Basic Map Creation

Setting initial capacity, map with different data types.

To create a map with make , define the key and value types and optionally, the initial capacity. The basic syntax is straightforward and easy to use.

For optimal performance, especially with large maps, set an initial capacity . This step helps in minimizing reallocations as the map size increases.

You can use various data types for both keys and values, offering flexibility based on your specific requirements.

In Go, setting and retrieving values in a map is a straightforward process. It's crucial to understand the syntax and methods for these operations to effectively manage the data stored in your maps.

Setting Values

Retrieving values, checking for key existence, deleting key-value pairs.

To set a value in a map, use the assignment operator. Specify the key and assign the corresponding value. This operation adds a new key-value pair to the map or updates the value of an existing key.

Retrieving a value is as simple as providing the key. The map returns the value associated with the given key. If the key does not exist, the map returns the zero value for the map's value type.

When retrieving values, it's often necessary to check if a key exists in the map to avoid working with zero values unintentionally.

To remove a key-value pair from a map, use the delete function. This function takes the map and the key as arguments and removes the key-value pair from the map.

In Go, error handling is a vital aspect of working with maps and the make function. Proper error handling ensures the robustness and reliability of your code, preventing unexpected behavior and making debugging easier.

Invalid Capacity

Non-existent key access, key deletion.

When using the make function, providing an invalid capacity , such as a negative number, does not throw an error but can lead to unexpected behavior. It's crucial to validate the capacity before using it to create a map.

Accessing a non-existent key in a map does not result in an error in Go. Instead, it returns the zero value for the value type of the map. To avoid this, always check for the existence of a key before accessing its value.

Deleting a non-existent key also does not result in an error in Go. However, it's a good practice to ensure the key exists before attempting to delete it to avoid confusion and ensure code clarity.

In Go, practical examples can significantly enhance understanding and usage of the make function for map creation. Let’s explore some real-world scenarios where make is used to create and manage maps effectively.

Creating A Map For A Word Count

Storing and retrieving user information, mapping relationships.

In text processing, you might need to count the occurrences of each word in a text. A map is perfect for this task, with words as keys and counts as values.

In applications, storing user information is a common requirement. A map can hold this data, with usernames or IDs as keys and user data as values.

In various scenarios, you might need to map relationships between different entities. A map can efficiently represent these relationships.

Each of these practical examples demonstrates the versatility and utility of using the make function to create maps in Go, catering to various real-world programming needs.

How can I delete a key-value pair from a map in Go?

You can use the delete function to remove a key-value pair from a map in Go. Provide the map and the key as arguments to the delete function.

Can I use negative numbers for the initial capacity of a map with make ?

No, using a negative number for the initial capacity of a map with make is not allowed and will lead to a runtime panic.

How can I check if a key exists in a map before accessing its value?

You can use the two-value assignment to check if a key exists in a map. For example: value, exists := myMap["key"] . The exists variable will be a boolean indicating whether the key is present in the map.

Let’s test your knowledge!

What is the `make` function used for in Golang?

Continue learning with these golang guides.

  • How To Work With Golang GRPC Efficiently
  • How To Work With Golang Array
  • How To Work With Golang Assert For Effective Testing
  • How To Utilize Golang Map Efficiently
  • How To Implement Golang Generics Efficiently

Subscribe to our newsletter

Subscribe to be notified of new content on marketsplash..

Table of Contents

How to create maps in golang, creating an empty map, how to iterate over a map, accessing map elements, updating and adding map elements, remove element from map, check for specific elements in a map, maps are reference types, length of map, maps equality, the supreme guide to golang maps.

The Supreme Guide to Golang Maps

A map is an unordered and changeable collection of key-value pairs. The map data structure is used for fast lookups, retrieval, and deletion of data based on keys. It is one of the most picked data structures in computer science.

Golang_Maps_1

It maps keys to values. The keys are unique identifiers within a map, while the values may not be. A map key can have the data type for which the equality operator (==) is defined. The data types are:

Types such as Slices, Maps and Functions are invalid as equality operator (==) is not defined for them. Go provides a built-in map type with a default value of nil. This article will educate you how to use Golang’s built-in map type.

Here's How to Land a Top Software Developer Job

Here's How to Land a Top Software Developer Job

Using the Map Literal:

Map with key-value pair

map[Key_Type]Value_Type{key1: value1, ..., keyN: valueN}

Golang_Maps_2.

Using Make Function

A map can also be created by passing the type of key and value to the make() function. It is an inbuilt function. With the following syntax, we can create a new map.

make(map[type of key]type of value) 

Golang_Maps_4

Basics to Advanced - Learn It All!

Basics to Advanced - Learn It All!

We can create an empty map by following two ways. One is by using the make() function and the other by using the map literal.

The zero or default value of a map is nil. A run-time panic will occur if you try to add elements to a nil map. Hence the map has to be initialized before adding elements. As we already know, the make() function always returns an initialized map. So we can add value to it.

Golang_Maps_6

Using the range for loop, we can iterate over a map. The values printed through the loop may vary because the map is an unordered collection.

Golang_Maps_8.

We can access the map elements with the following syntax.

value = map_name[key]

Golang_Maps_10

We can update and add the map elements with the following syntax.

map_name[key] = value

We can remove the map elements using the delete() function.

delete(map_name, key)

Golang_Maps_14

We can check if a certain key exists in a map with the following syntax.

val, ok :=map_name[key]

We can use the blank identifier (_) in place of val, to check the existence of a certain key.

Golang_Maps_16

Maps are reference types. When you assign a map to a new variable, both refer to the same underlying data structure. The changes done by one variable will affect the content of the other.

Golang_Maps_18

We can find the length of a map using the len() function. The len() function calculates the number of elements in a map. 

Golang_Maps_20

Maps can be compared by checking each one's individual elements one by one. It can't be compared using the == operator. The == operator only works to check if a map is nil.

Golang_Maps_22

Master front-end and back-end technologies and advanced aspects in our Post Graduate Program in Full Stack Web Development . Unleash your career as an expert full stack developer. Get in touch with us NOW!

In this tutorial, we learned how to create and initialize and declare maps, how to create an Empty Map, how to iterate over a Map, how to access map elements, how to update and add map elements, remove elements from map and a lot more operations of Map. This article is comprehensive, covering all the key topics relating to Map in Golang. 

If you aim to build a software development career , you can check the Post-Graduate Program in Full Stack Development by Simplilearn . It can be the ideal solution to help you develop your career in the right direction.

In case you have queries or would like to provide your input to our editorial team regarding this “The Supreme Guide to Golang Maps” tutorial, feel free to use the comments section below. Our team of SMEs will get back to you soon!

Our Software Development Courses Duration And Fees

Software Development Course typically range from a few weeks to several months, with fees varying based on program and institution.

Recommended Reads

Free Mind-Map: Salesforce Mind Map

Working With Map in Python

The Supreme Guide to Golang Interface

Free Mind-map: PMP Certification

An Introduction to C++ Map

The Supreme Guide to Go Concurrency

Get Affiliated Certifications with Live Class programs

Post graduate program in full stack web development.

  • Live sessions on the latest AI trends, such as generative AI, prompt engineering, explainable AI, and more
  • Caltech CTME Post Graduate Certificate

Full Stack Web Developer - MEAN Stack

  • Comprehensive Blended Learning program
  • 8X higher interaction in live online classes conducted by industry experts

Full Stack Java Developer Job Guarantee Program

  • 8X higher engagement in live online classes by industry experts
  • Industry recognized certification
  • PMP, PMI, PMBOK, CAPM, PgMP, PfMP, ACP, PBA, RMP, SP, and OPM3 are registered marks of the Project Management Institute, Inc.
  • Our Podcast
  • +1-888-886-7343

GoLang Map Tutorial: A Step-by-Step Guide to Creating Maps in GoLang

assign to map golang

Maps are a very powerful and versatile tool for any programmer in any language. GoLang is no exception.

If you want to know how to use this specific data structure in GoLang, you can use the following 6 simple steps to learn how to create and manipulate maps in your own GoLang projects.

But first, let’s go over what maps are and how they are used.

  • Understanding GoLang Maps: An Overview

A Map in GoLang is a data structure that allows you to store data indexed by a unique key. It is an efficient way to store and retrieve data that needs to have an unique identifier.

This functionality shines in real-world scenarios where data needs to be quickly accessed, updated, or managed based on unique identifiers, like managing a database of customer records where each customer has a unique ID. Compared to other data structures like arrays or slices, GoLang Maps offers a speedier look-up for values based on keys, which is a significant advantage.

While the idea of Maps isn’t unique to GoLang and is shared across various programming languages like Python or Java, the implementation and syntax may exhibit variances. For instance, the basic syntax of a GoLang Map is map[KeyType]ValueType , representing the type of keys ( KeyType ) and the type of values ( ValueType ) the map will hold. This simple yet powerful structure forms the crux of many data management operations in GoLang, making it a vital concept to grasp in this GoLang tutorial.

As we delve deeper into the next sections, you’ll learn the steps to create and manipulate GoLang Maps, unlocking the potential to handle data efficiently in your GoLang projects.

Hire a Golang Developer

  • 6 Simple Steps to Create a GoLang Map

Creating and manipulating maps is actually quite simple. Let’s delve into this Golang tutorial where we’ll go over what you need to know in order to use them and how to create one.

Map Structure in GoLang

Maps are containers consisting of key-value pairs. The ‘key’ is used as an indexer for the rest of the data, or our ‘value’.

The advantage of a map is that the keys do not have to be sequential and can be inserted in any order. When any key is inserted, the map internally takes care of indexing it in a way that makes future searches fast and efficient.

1. Initializing a Map

Before using a map, you have to initialize it. There are two main ways to do this.

Method 1: Declare and Make

make() is a built-in function of Go that is used to allocate and initialize a complex data structure, such as a map. If you try to use a map before ‘making’ it, an error will occur.

This method declares the map variable, and the map has no entries.

Declare and then make

This is useful in case you need to declare the map before allocating and initializing it in some later part of your code.

Declare and make in the same line

Or you can use the short variable declaration operator (‘:=’).

The map becomes immediately available to be manipulated further.

Method 2: Declare and Initialize

In this case, the map is declared and immediately filled with any number of entries you require.

Practical Example

We’ll be doing a practical example by developing a simple program that keeps track of the patrons of a library. We’ll be using a map to store our library’s patrons. Their Patron ID will be our ‘key’, and their name our ‘value’. The patron ID will be a simple integer, and their name a string.

Since we already want to have some patrons in our library, we’ll declare and initialize straight away.

Mr. Terrence and Ms. Evelyn work at the library and also use it, so they are our first patrons to be registered.

We’ll import the fmt package from now on so we can print our map’s contents to the screen.

The output is:

2. Adding to a Map

Adding to a map is simple. All you need to do is assign a value to a key on a map. Remember that keys are unique and cannot repeat. If the key already exists, the assignment will replace the existing value.

New patrons are now registering in our library, so we’ll add them to our map and give them unique IDs.

3. Retrieving a Value from a Golang Map

If you want to retrieve a value from a map, you do it using the key, like so:

Let’s see who our patron 1 is.

4. Iterating a Map

Iterating maps is usually done with a for loop combined with the range keyword.

If you don’t care about a specific part of the key-value pair, you can use the blank identifier (‘_’) instead of declaring a variable.

We’ve seen that you can print a whole map at once using fmt.Println() , but let’s format it a little better by ourselves, and also provide some more information about our data.

5. Checking if an entry exists on a Map

When we try to get a value from a map, it also returns a boolean that tells us if the key exists in the map or not. We can then use it to make checks and have code ready that is tailored to either scenario where the key exists or doesn’t.

If the value is irrelevant to what you want to do and you just want to check that the key exists on the map, you can use the blank identifier .

Let’s check our patrons and see if an ID is being used and if so, by whom.

6. Removing an entry from a Golang Map

To remove a key-value pair on a map, all you need to do is use the built-in function delete() .

Mr. Terrence is moving away and unfortunately will no longer be working at the library. As such, we need to remove him from our patrons.

Remember: GoLang Maps are reference types

This is useful to remember if you’re assigning a map to another variable. Manipulating that new variable will also change the original map.

Imagine we wanted to have separate dedicated lists for our patrons and our staff, but still include our staff as our patrons, since they also use the library.

This clearly would not work. We’d need to have two separate lists with repeat entries.

  • Common Mistakes When Working with GoLang Maps and How to Avoid Them

Working with maps in GoLang can be straightforward once you grasp the basics, but there are common pitfalls that developers, especially those new to GoLang, may stumble upon. Here’s a roundup of some common mistakes and how you can sidestep them:

1. Not Initializing Maps Before Use:

GoLang maps need to be initialized before they can be used.

  • Solution: Always initialize your maps using the make function or a map literal.

2. Assuming Order in Map Iteration:

Maps in GoLang do not maintain an order of elements. Assuming an order during iteration is a mistake.

  • Solution: If order is crucial, consider using a slice to maintain order or a sorted map implementation.

3. Modifying Maps During Iteration:

Modifying a map while iterating over it can cause errors.

  • Solution: Collect the keys or values you want to modify in a separate slice, then iterate over that slice to make changes to the map.

4. Ignoring the ok Check:

When accessing an element, it’s good practice to perform an ok check to see if the key exists in the map to avoid zero-value errors.

  • Solution: Always perform the ok check when accessing map elements.

By being aware of these common missteps and applying the outlined solutions, you’ll be on a surer footing when working with GoLang maps, making your coding journey smoother and bug-free.

Maps are extremely versatile tools that help you index and search through data efficiently and easily. We hope we’ve given you a comprehensive primer on how Go Maps work and how you can use them in your projects.

Go is a very easy-to-use language that is growing rapidly in terms of usage by many high profile companies. If you’re looking to hire Go developers , DistantJob can help you find the perfect fit for your needs.

assign to map golang

Joana Almeida

Let’s talk about scaling up your team at half the cost!

Discover the advantages of hassle-free global recruitment. Schedule a discovery call with our team today and experience first-hand how DistantJob can elevate your success with exceptional global talent, delivered fast.

Subscribe to our newsletter and get exclusive content and bloopers

or Share this post

Related Articles

assign to map golang

Visual Studio vs Visual Studio Code: What’s the Key Difference? 

The choice between Visual Studio and Visual Studio Code (VSCode) is a common topic of discussion among developers, and for a good reason. Both are […]

assign to map golang

Coder vs Programmer: What’s the Difference? 

When you’re in the hiring process for a tech role, semantics can have a huge impact on who applies to the job. Adding the word […]

assign to map golang

C# vs. Java: What Are Its Main Differences

Both Java and C# occupy a solid position in the world of back-end development, cloud apps, Windows client applications, and big data processing among many […]

Reduce Development Workload And Time With The Right Developer

When you partner with DistantJob for your next hire, you get the highest quality developers who will deliver expert work on time. We headhunt developers globally; that means you can expect candidates within two weeks or less and at a great value.

Increase your development output within the next 30 days without sacrificing quality.

Book a Discovery Call

Want to meet your top matching candidate?

Find professionals who connect with your mission and company..

pop-up-img

Talk with a senior recruiter.

Fill the empty positions in your org chart in under a month..

By continuing to browse the site you are agreeing to our use of cookies .

assign to map golang

GoLinuxCloud

Learn to Clone or Copy Map in GO Like a PRO [5 Methods]

In the vast and versatile world of Go (Golang) programming, one often encounters the necessity to replicate data structures, ensuring that modifications in the replica do not affect the original. This necessity brings us to the concepts of copy map and clone map. When we talk about copying or cloning a map in Go, we refer to the creation of a duplicate map, possessing the same keys and values as the original. This duplication process is essential in various scenarios, such as preserving the original map’s state, preventing unauthorized modifications, or performing operations on the map without altering the actual data.

In this tutorial we will explore different methods which can be used to copy map or what we can also term as clone map in Golang.

Different Methods to Copy Map in GO

Here are various methods you can use to copy or clone a map in Go (Golang):

  • Using Range Loop with Make : A simple method where a new map is initialized, and elements from the original map are iterated over and assigned to the new map, ensuring a separate memory allocation.
  • Using JSON Marshalling and Unmarshalling : This technique involves converting the original map into a JSON object and then converting it back into a new map, ensuring that the new map is a separate entity.
  • Using Deep Copy with Third-Party Packages : Utilizing available third-party packages that offer deep copy functionalities, ensuring that nested maps or maps with reference types are effectively cloned.
  • Using Reflection : Employing the reflect package to dynamically create a new map and populate it with the elements of the original map, catering to various data types.
  • Custom Implementation Based on Type : Crafting specific functions or methods tailored to the types stored in the map, ensuring an effective copying process tuned to the map's content.

Deep Copy vs Shallow Copy

When you copy map elements in Go, it’s essential to understand the difference between a deep copy and a shallow copy. The distinction lies in how the map's contents, particularly reference types like slices, maps, and pointers, are duplicated.

A deep copy creates a new map with not only the immediate elements of the original map being duplicated but also the underlying elements of any reference types recursively copied. This means that modifications to the nested elements in the copied map won’t affect the original map.

Situations where Deep Copy is applicable:

  • When the map contains reference types like slices , maps, or pointers, and you want to manipulate them without affecting the original map.
  • When you need complete isolation between the original and copied map.

Example of Deep Copy:

In this example, a deep copy of the map is made, and modifying the copied map does not affect the original map.

Shallow Copy

A shallow copy duplicates the immediate elements of the original map into a new map, but the reference types within the map still point to the same memory locations as those in the original map.

Situations where Shallow Copy is applicable:

  • When you only need to modify the top-level elements of the map and want to maintain links to the original nested structures.
  • When full isolation between the original and copied map is not necessary.

Example of Shallow Copy:

In this example, a shallow copy of the map is made. Modifying the copied map's slice also affects the original map because the slice's underlying array is still shared between both maps.

1. Using Range Loop with Make

When you want to copy map elements in Go, one straightforward approach is utilizing a range loop in conjunction with the make() function. Here’s how it works:

Performing Shallow Copy

In a shallow copy, the outermost objects are duplicated, while the inner elements retain references to the same memory locations as the original map’s inner elements.

Here, both the original and copied maps refer to the same memory locations of the inner elements. Modifying the copied map also modifies the original map.

Performing Deep Copy

A deep copy means cloning every item recursively, ensuring that no memory locations of the inner elements are shared between the original and copied map.

Modifying the copied map doesn’t affect the original map because every element, including the inner slices, has been recursively cloned.

We can also declare the copyMap logic inside a function to make it re-usable:

2. Using JSON Marshalling and Unmarshalling

JSON Marshalling and Unmarshalling can also be used to copy map contents in Go. This method involves converting the map into a JSON string (marshalling) and then creating a new map by parsing the JSON string back (unmarshalling). This is more commonly used for deep copying and it is not so straight forward to perform shallow copy using this method.

By default, using JSON marshalling and unmarshalling performs a deep copy because the data is serialized and deserialized into a new memory allocation .

3. Using Third-Party Package (copier)

The copier package primarily focuses on struct copying but can also be utilized for maps, primarily resulting in deep copying behavior. Here's how you can use copier for copying maps:

In this example, even though pointers are used, copier creates a new instance of the ValueStruct , making the copiedMap independent of the originalMap . This is essentially a deep copy, as modifications to the copiedMap do not affect the originalMap .

The copier package might not directly support a shallow copy in terms of retaining the original pointers. For a shallow copy, you might need to use a different approach or package.

4. Using Reflection

Reflection in Go is a powerful tool that allows for inspection and modification of variable types and values at runtime. It’s more complex and might not be the most performance-efficient way of copying maps, but it offers flexibility. Here’s how you could employ reflection to accomplish both shallow and deep copy tasks:

A shallow copy creates a new map, but the elements inside the map might still refer to the same memory locations as the original map.

A deep copy using reflection involves recursively copying each element, ensuring that the original and copied maps don’t share references.

In these examples, functions shallowCopyMap() and deepCopyMap() utilize reflection to perform the copy operations.

Note that using reflection might not be the most performant choice due to the dynamic type checking and recursive calls involved, especially in a deep copy. However, reflection provides a generic way to copy or clone maps, even when the exact types are not known at compile-time, offering a degree of flexibility and generality in handling various data structures.

5. Custom Implementation Based on Type

Creating a custom implementation based on types allows for a more targeted approach in copying maps. It gives you the flexibility to define the copying process, specifically according to the types and structures you are dealing with.

Creating a shallow copy of a map based on specific types involves duplicating the outer map while keeping references to the same inner elements.

Creating a deep copy of a map based on specific types involves duplicating not only the outer map but also the inner elements, ensuring no shared references.

In these examples, shallowCopyIntMap and deepCopyStructMap functions are designed specifically based on the data types in the maps.

Frequently Asked Questions (FAQs)

What does it mean to "copy a map" in Go?

Copying a map in Go refers to creating a new map that contains all the keys and values of the original map. Depending on how you choose to copy the map, the new map might share references to the same underlying data (shallow copy) or have completely separate data (deep copy).

What is the difference between a "shallow copy" and a "deep copy" of a map in Go?

A shallow copy of a map involves creating a new map with new keys, but the values still hold references to the same objects as the original map. In a deep copy, a new map is created with new keys, and new objects are also created for the values, ensuring no shared references with the original map.

How do you perform a shallow copy of a map in Go?

A shallow copy can be performed using a simple loop to copy keys and values from the original map to a new one, for instance using the range loop. The new map gets filled with the keys and values of the original map, but the values (if they are reference types like slices or maps) still point to the same memory locations.

How do you perform a deep copy of a map in Go?

A deep copy can be achieved using various methods such as manually creating new objects for each value, utilizing the encoding/json package to marshal and unmarshal the map, or using third-party libraries that offer deep copying functionalities like copier .

When should I use a shallow copy, and when should I use a deep copy?

Use a shallow copy when it’s acceptable to have the copied map's values point to the same references as the original map’s values. Choose a deep copy when you want the copied map to be entirely independent of the original map, with no shared references, ensuring changes in the copied map do not affect the original map.

Is it possible to copy maps of custom structs in Go?

Yes, you can copy maps with custom structs as values. When copying, you can choose whether to perform a shallow copy, where the struct references are shared, or a deep copy, where new struct instances are created for the copied map.

Are there any third-party libraries that help in copying maps in Go?

Yes, there are third-party libraries, like copier or go-cmp , which provide functionalities to easily perform shallow and deep copies of maps and other data structures in Go. Before using a third-party library, ensure it is well-maintained and widely accepted by the community for reliability and performance.

Does Go have built-in support for deep copying maps?

Go doesn’t have a built-in function specifically for deep copying maps. However, you can achieve deep copying by using various techniques such as the encoding/json package for marshaling and unmarshaling maps, creating custom functions, or using third-party libraries.

In conclusion, copying or cloning maps in Go can be accomplished through various methods, each with its unique applications and considerations. The fundamental distinction lies between performing a shallow copy and a deep copy. A shallow copy is simpler and entails replicating the map's structure and entries, but not deeply duplicating nested reference types, leading to shared references. In contrast, a deep copy creates a completely independent copy of the map, ensuring that all nested elements, even those of reference types, are independently replicated without sharing memory references.

Different techniques, ranging from using simple range loops, JSON marshaling and unmarshaling, reflection, custom type-based implementations, to employing third-party packages, offer a spectrum of tools to achieve the desired level of copying. The selection of a suitable method is guided by various factors such as the necessity to maintain or sever reference linkages between the original and copied maps, performance considerations, and the specific data types and structures involved.

For more information and official documentation on maps in Go, refer to the following links:

  • Go Maps in Action - A blog post that goes deep into maps, providing a fundamental understanding.
  • Go by Example: Maps - An illustrative guide that walks through the basics of using maps in Go.
  • Go Documentation: Map Type - The official Go documentation describing the map type.

Learn to Clone or Copy Map in GO Like a PRO [5 Methods]

He is proficient in Golang, Python, Java, MongoDB, Selenium, Spring Boot, Kubernetes, Scrapy, API development, Docker, Data Scraping, PrimeFaces, Linux, Data Structures, and Data Mining. With expertise spanning these technologies, he develops robust solutions and implements efficient data processing and management strategies across various projects and platforms.

Can't find what you're searching for? Let us assist you.

Enter your query below, and we'll provide instant results tailored to your needs.

If my articles on GoLinuxCloud has helped you, kindly consider buying me a coffee as a token of appreciation.

Buy GoLinuxCloud a Coffee

For any other feedbacks or questions you can send mail to [email protected]

Thank You for your support!!

Leave a Comment Cancel reply

Save my name and email in this browser for the next time I comment.

Notify me via e-mail if anyone answers my comment.

  • Data Types in Go
  • Go Keywords
  • Go Control Flow
  • Go Functions
  • GoLang Structures
  • GoLang Arrays
  • GoLang Strings
  • GoLang Pointers
  • GoLang Interface
  • GoLang Concurrency

Related Articles

  • Solve Coding Problems
  • How to serialize a Map in JavaScript ?
  • How to iterate over Map elements in JavaScript ?
  • How are elements ordered in a Map in JavaScript ?
  • What is JavaScript Map and how to use it ?
  • How to sort a map in JavaScript ?
  • How to map array values without using map method in JavaScript ?
  • What is the difference between Map and WeakMap in JavaScript ?
  • How to convert Map keys to an array in JavaScript ?
  • How to convert a plain object into ES6 Map using JavaScript ?
  • How to use map() on an array in reverse order with JavaScript ?
  • How to use map and filter simultaneously on an array using JavaScript ?

How to copy a map to another map in Golang?

  • How to use map(), filter(), and reduce() in JavaScript ?
  • How to map an array in Coffeescript ?
  • Difference between forEach() and map() loop in JavaScript
  • How to skip over an element in .map() ?
  • How to switch CSS class between buttons rendered with map()?
  • How to call the map method only if the element is an array?

Please Login to comment...

  • Golang-Program
  • Go Language

Improve your Coding Skills with Practice

 alt=

What kind of Experience do you want to share?

💕 Copy a map in Go

Maps in Go are reference types , so to deep copy the contents of a map, you cannot assign one instance to another. You can do this by creating a new, empty map and then iterating over the old map in a for range loop to assign the appropriate key-value pairs to the new map. It is the simplest and most efficient solution to this problem in Go.

As you see in the output, the copied map is a deep clone, and adding new elements does not affect the old map.

Be careful when making a shallow copy by assigning one map to another. In this case, a modification in either map will cause a change in the data of both maps.

Thank you for being on our site 😊. If you like our tutorials and examples, please consider supporting us with a cup of coffee and we'll turn it into more great Go examples.

Have a great day!

🗝️ Check if a map contains a key in Go

Learn how to check if a key exists in a map, 🫘 count the occurrences of an element in a slice in go, learn how to count elements in a slice that meet certain conditions, ❤️‍🩹 recover function in go, learn what it is for and how to use the built-in recover() function.

You are viewing this page in an unauthorized frame window.

This is a potential security issue, you are being redirected to https://nvd.nist.gov

You have JavaScript disabled. This site requires JavaScript to be enabled for complete site functionality.

Official websites use .gov A .gov website belongs to an official government organization in the United States.

Information Technology Laboratory

National vulnerability database.

  • Vulnerabilities

NIST is currently working to establish a consortium to address challenges in the NVD program and develop improved tools and methods. You will temporarily see delays in analysis efforts during this transition. We apologize for the inconvenience and ask for your patience as we work to improve the NVD program.

Weakness Enumeration

Change history, new cve received by nist 2/17/2024 12:15:10 am.

assign to map golang

Beginner's Guide: How to Play

Skull and Bones throws a ton of systems and materials at you early into your pirate journey. It can be difficult to get a good grasp on all of the systems with so much thrown at you to start out, but here are a few of the most important things to know at the start of your adventure.

Loot As Much Booty As Possible

SB Loot.jpeg

While you do have a limited amount of storage in your ship's cargo hold, you should still loot anything and everything you come across. As you sail around you can find loot just floating in the water and you can harvest materials from rock formations, trees, bushes, and more. Pretty much every item in Skull and Bones serves some purpose, whether it's crafting or selling for Silver. Crafting materials in particular are needed in abundance to really deck out your ship with weapons or build a new ship entirely. Food items can be used to refill your stamina while out at sea and salvage parts are used to make Repair Kits to keep your vessel afloat.

Bountiful Treasure

Every pirate needs treasure and in the case of Skull and Bones, that takes the form of Silver. Silver is needed to purchase blueprints and to craft new ships, furniture, and weapons. You're going to need a healthy amount of Silver, and there are a few ways to get it. While completing contracts and taking out enemy ships will earn you some Silver, the best way to earn it is by selling commodities.

Commodities are a specific type of item that you can loot or purchase from commodity traders at some outposts. These items sell for a decent amount of Silver, but you can actually sell them for even more, if you head to a region where they are in higher demand. If you zoom out the map to the second highest level, the side tab will display which items are in high demand in the region you are hovering over. Selling those items in that region will net you more Silver, with green arrows shown next to the item on the sell screen.

Take Down Enemy Ships Frequently, Regardless Of Level

SB Ships.jpeg

In Skull and Bones there are no downsides to taking out enemy ships, especially ones lower level than you. Not only do the ships typically have loot and Silver on board, but you earn Infamy for taking them out. Reaching higher Infamy ranks gives you access to better blueprints, which lets you craft better ships, weapons, and furniture. All of these can increase the level of your own ship making you a more fearsome pirate.

It appears that regardless of the difference in level, taking out an enemy ship still rewards a decent amount of Infamy. There doesn't appear to be a fall off for taking out low-level ships, so its worth taking the time to put a few cannonballs to anyone in your path.

Gather Blueprints Whenever Possible

There are vendors and merchants everywhere in Skull and Bones, both a big ports like Sainte-Anne and at smaller locations you can drop anchor. Many of these merchants are typically selling blueprints, with the selection unique to each vendor. Blueprints are necessary to make everything in the game, like weapons, ships, and furniture.

Each specific blueprint can be found in one of two places, depending on the blueprint itself. They can be found at a specific vendor, with each unique blueprint sold by only one vendor. The second option depends on the blueprint itself, but they can sometimes be earned by completing a contract or by looting an enemy ship. The biggest hurdle here is that you need to be a high enough Infamy level to buy certain blueprints, so you may have to remember to come back to a vendor after leveling.

  • There is a small arrow on the speed display. That arrow shows which direction the wind is blowing. Sailing into slow you down and sailing with it gives you a speed boost.
  • If you want to skip the harvesting mini-game, you can turn on auto-harvest in the settings.
  • If you select an unlocked blueprint from the codex you can track the needed materials. This will mark places to find them on your map.
  • When tracking a mission that requires you to deliver items, the tracker will count items in your storage while docked, but you will need to move them to your cargo before setting sail.
  • Upgrade your weapons and hull whenever possible and craft better ships as soon as they become available. Crafting higher tier ships will give you a big boost to your stats that will make it easier to explore new areas.
  • Contracts given out on the job board and bounty board are not unique quests, but randomly generated. These contracts will have a time-limit on them and usually only reward Silver for your efforts.

Up Next: All Ships And How To Get Them

Top guide sections.

  • Skull and Bones Raging Tides: Season 1 Release Date and Details
  • How To Plunder Loot
  • How to Get Sovereigns
  • How To Get Pieces Of Eight And Where To Spend Them

Was this guide helpful?

In this guide.

Skull and Bones

IMAGES

  1. Golang Tutorial For Beginners

    assign to map golang

  2. Golang Map

    assign to map golang

  3. Golang Tutorial #15

    assign to map golang

  4. Learn Maps in Golang (with examples)

    assign to map golang

  5. GoLang Tutorial

    assign to map golang

  6. Golang Maps example

    assign to map golang

VIDEO

  1. Golang Net/Http Tutorial Part 1

  2. 【Go语言中文入门教学】map哈希字典

  3. map-reduce basic implementation in golang

  4. Internals of Maps in Golang

  5. Learning Golang To Cure My Crippling Depression

  6. TaleSpire Map Generated Using Georeferencing Data

COMMENTS

  1. Go maps in action

    To initialize a map, use the built in make function: m = make (map [string]int) The make function allocates and initializes a hash map data structure and returns a map value that points to it. The specifics of that data structure are an implementation detail of the runtime and are not specified by the language itself.

  2. A safe way to add a key to map in Golang

    A safe way to add a key to map in Golang Asked 5 years, 7 months ago Modified 5 years, 7 months ago Viewed 35k times 0 Due to this fact: If a map entry is created during iteration, that entry may be produced during the iteration or may be skipped. The choice may vary for each entry created and from one iteration to the next.

  3. Maps explained: create, add, get, delete ¡ YourBasic Go

    A map (or dictionary) is an unordered collection of key-value pairs, where each key is unique. You create a new map with a make statement or a map literal. The default zero value of a map is nil . A nil map is equivalent to an empty map except that elements can't be added.

  4. How to make and use maps in Golang

    Published: 28 Nov 2022 In computer programming, a map is a data structure that stores key-value pairs. Each key is paired with a corresponding value, which is retrieved by referencing the key. Programmers often choose to work with maps for their computational efficiency.

  5. Go map (With Examples)

    Output map [Golang:85 Java:80 Python:81] Here, we have created a map and printed the key-values of a map. Note: We can also create a map using var keyword.

  6. Go by Example: Maps

    The builtin delete removes key/value pairs from a map. delete (m, "k2") fmt. Println ("map:", m) To remove all key/value pairs from a map, use the clear builtin. clear (m) fmt. Println ("map:", m) The optional second return value when getting a value from a map indicates if the key was present in the map.

  7. Go map

    Go map tutorial shows how to work with maps in Golang. A map is an unordered collection of key/value pairs, where each key is unique. Maps are also called dictionaries, associative arrays, or hash tables. ... It means that when we assign a reference to a new variable or pass a map to a function, the reference to the map is copied. reference.go.

  8. Understanding Maps in Go

    A map is constructed by using the keyword map followed by the key data type in square brackets [ ], followed by the value data type. The key-value pairs are then placed inside curly braces on either side { }: map [ key] value {} You typically use maps in Go to hold related data, such as the information contained in an ID.

  9. Maps in Golang

    Working with maps in Golang. We can insert, delete, retrieve keys in a map. Let's see how to do that. 1. Inserting elements in a map. You can insert keys in two ways. Either insert keys when initializing or use index syntax to initialize. 2. Getting values from a map.

  10. Golang Maps

    Simple: In this method, you can create and initialize a map without the use of make () function: Creating Map: You can simply create a map using the given syntax: // An Empty map map [Key_Type]Value_Type {} // Map with key-value pair map [Key_Type]Value_Type {key1: value1, ..., keyN: valueN} Example: var mymap map [int]string

  11. Go maps: declaring and initializing

    0 What is a Golang map? Why is it useful? How does it compare to a slice? How do you declare a map? How do you initialize a map in Go? Fear not, all these questions are answered in this friendly introduction to one of Go's most powerful features.

  12. How To Use Golang Make Map Effectively

    The general syntax for using the make function with maps is: mapVariable := make(map[ KeyType] ValueType, initialCapacity) 📌 mapVariable: The name of the map variable. KeyType: The type of key that the map will use. ValueType: The type of value that the map will store. initialCapacity: (Optional) Initial capacity hint for the map. For instance:

  13. The Supreme Guide to Golang Maps

    Maps are reference types. When you assign a map to a new variable, both refer to the same underlying data structure. The changes done by one variable will affect the content of the other. Length of Map. We can find the length of a map using the len() function. The len() function calculates the number of elements in a map.

  14. Creating Maps in GoLang: Step-by-Step Tutorial

    Before Mr. Terrence Leaves: map[0:Terrence 1:Evelyn] After Mr. Terrence Leaves: map[1:Evelyn] Remember: GoLang Maps are reference types. This is useful to remember if you're assigning a map to another variable. Manipulating that new variable will also change the original map.

  15. Learn to Clone or Copy Map in GO Like a PRO [5 Methods]

    Here are various methods you can use to copy or clone a map in Go (Golang): Using Range Loop with Make: A simple method where a new map is initialized, and elements from the original map are iterated over and assigned to the new map, ensuring a separate memory allocation.

  16. How to copy a map to another map in Golang?

    Let us discuss this concept with the help of the examples: Example 1: package main import "fmt" func main () { originalMap := make (map [string]int) originalMap ["one"] = 1 originalMap ["two"] = 2 originalMap ["three"] = 3 originalMap ["four"] = 4 originalMap ["five"] = 5 originalMap ["six"] = 6 originalMap ["seven"] = 7 originalMap ["eight"] = 8

  17. Copy a map in Go (Golang)

    You can do this by creating a new, empty map and then iterating over the old map in a for range loop to assign the appropriate key-value pairs to the new map. It is the simplest and most efficient solution to this problem in Go. As you see in the output, the copied map is a deep clone, and adding new elements does not affect the old map.

  18. go

    package main import "fmt" func main () { // Data struct containing an interface field. type Data struct { internal interface {} } // Assign a map to the field. type myMap map [string]interface {} data := Data { internal: make (myMap), } // Now, we want to access the field again, but as a map: // check that it matches the type we w...

  19. Nvd

    Although a CVE ID may have been assigned by either CVE or a CNA, it will not be available in the NVD if it has a status of RESERVED by CVE. Please check the CVE dictionary first, and if you have further questions about a specific CVE and when it will be available, please contact [email protected] directly. NIST is currently working to establish a ...

  20. Beginner's Guide: How to Play

    Beginner's Guide: How to Play. Skull and Bones throws a ton of systems and materials at you early into your pirate journey. It can be difficult to get a good grasp on all of the systems with so ...

  21. How to add data to a map of maps in Golang?

    2 Answers Sorted by: 29 It is here: data ["Date_2"] ["Sistem_A"] ["command_5"] = "violet" The expression data ["Date_2"] will return a nil-map. It is never initialized, so looking for the index ["Sistem_A"] panics. Initialize the map first:

  22. How do we create an empty map and append new data in golang?

    -1 I'm having a problem with creating an empty map and append new data to it while looping on another map. this is the error i'm getting on my IDE. here's my data struct to be added to the map.