How to Iterate Over Keys in a Map in Go - Step by Step Examples

How to Iterate Over Keys in a Map in Go ?

Answer

To iterate over keys in a map in Go, you can use a range-based for loop. This allows you to access each key in the map.

✐ Examples

1 Iterating Over Keys Using Range-Based For Loop

We can iterate over keys in a map in Go using a range-based for loop, which provides a convenient syntax for iterating over all keys in the map.

For example,

We start by declaring and initializing a map named myMap with some key-value pairs. In this example, the map has string keys and integer values.
We use a range-based for loop to iterate over the map. The loop extracts the key from each key-value pair in the map.
We print each key to the console using the fmt.Println function to verify that we are iterating over all keys.

Go Program

package main

import "fmt"

func main() {
    // Declare and initialize a map
    myMap := map[string]int{
        "one": 1,
        "two": 2,
        "three": 3,
    }

    // Iterate over keys using range-based for loop
    for key := range myMap {
        fmt.Println(key)
    }
}

Output

one
two
three

2 Iterating Over Keys and Values Using Range-Based For Loop

We can iterate over keys and values in a map in Go using a range-based for loop, which provides a way to access both keys and values.

For example,

We start by declaring and initializing a map named myMap with some key-value pairs. In this example, the map has string keys and integer values.
We use a range-based for loop to iterate over the map. The loop extracts both the key and value from each key-value pair in the map.
We print each key and its corresponding value to the console using the fmt.Println function to verify that we are iterating over all keys and values.

Go Program

package main

import "fmt"

func main() {
    // Declare and initialize a map
    myMap := map[string]int{
        "one": 1,
        "two": 2,
        "three": 3,
    }

    // Iterate over keys and values using range-based for loop
    for key, value := range myMap {
        fmt.Println(key, value)
    }
}

Output

one 1
two 2
three 3

3 Storing and Iterating Over Keys Separately

We can store keys in a separate slice and then iterate over the slice in Go, which provides a way to work with keys independently of their values.

For example,

We start by declaring and initializing a map named myMap with some key-value pairs. In this example, the map has string keys and integer values.
We declare a slice named keys to store the keys from the map.
We use a range-based for loop to iterate over the map and append each key to the keys slice.
We use another range-based for loop to iterate over the keys slice and print each key to the console using the fmt.Println function to verify that we have stored all keys separately.

Go Program

package main

import "fmt"

func main() {
    // Declare and initialize a map
    myMap := map[string]int{
        "one": 1,
        "two": 2,
        "three": 3,
    }

    // Declare a slice to store the keys
    var keys []string

    // Store keys in the slice
    for key := range myMap {
        keys = append(keys, key)
    }

    // Iterate over the keys slice
    for _, key := range keys {
        fmt.Println(key)
    }
}

Output

one
two
three

Summary

In this tutorial, we learned How to Iterate Over Keys in a Map in Go language with well detailed examples.

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How to Iterate Over Keys in a Map in Go - Step by Step Examples