Maps (Associative Arrays) in Go¶

Dictionaries in Golang.

Go has a built-in map type, which are associative arrays.

Defining a Map¶

Basic Map Syntax¶

The basic syntax for defining a map:

var myMap map[key_type]value_type

First you call map to indicate that you're making a dictionary.
Then, you declare the key and value types.
Declare the key type inside the square brackets.
Declare the value type after the square brackets.

map[string]int will create a dictionary that maps strings to integers.
* E.g., { "a": 1 }

Example Map¶

This is a very basic example of implementing a map:

myMap := map[string]int{
    "key1": 1,
    "key2": 2,
}

fmt.Println(myMap["key1"]) // 1  
fmt.Println(myMap["key2"]) // 2

Example Usage¶

Very basic example of using a map inside of a struct:

type Person struct {
    Name    string  
    Age     int  
    Sex     string  
    Details map[string]any  
}

func NewPerson(name string, age int, sex string) {
    p := Person{
        Name: name,
        Age:  age,
        Sex:  sex,
    }
    // Make a map to store the details of the person  
    p.Details = make(map[string]any)  

    // Add the keys and values to the map  
    p.Details["name"] = p.Name  
    p.Details["age"] = p.Age  
    p.Details["sex"] = p.Sex  
}

Make the map by using make(map[key_type]value_type) inside of the
struct, and then add values to it.

A different way of doing this is to create a map variable and then assign it to p.Details.

Note: This is probably bad practice for performance, since it's making an entirely new map.

    details := map[string]any{
        "name": p.Name,
        "age": p.Age,
        "sex": p.Sex,
    }
    p.Details = details