How to Iterate Over Entries (Key-Value Pairs) in a Map in Go - Step by Step Examples

How to Iterate Over Entries (Key-Value Pairs) in a Map in Go ?

Answer

To iterate over entries (key-value pairs) in a map in Go, you can use a range-based for loop. This allows you to access each key-value pair in the map.

✐ Examples

1 Iterating Over Entries Using Range-Based For Loop

We can iterate over entries in a map in Go using a range-based for loop, which provides a convenient syntax for iterating over all key-value pairs 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 both the key and value from each key-value pair in the map.
We print each key and value to the console using the fmt.Println function to verify that we are iterating over all entries.

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 entries using range-based for loop
    for key, value := range myMap {
        fmt.Println("Key:", key, "Value:", value)
    }
}

Output

Key: one Value: 1
Key: two Value: 2
Key: three Value: 3

2 Iterating Over Keys and Values Separately

We can iterate over keys and values separately in a map in Go using two range-based for loops, which provides a way to work with keys and values independently of each other.

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 slices named keys and values to store the keys and values from the map separately.
We use a range-based for loop to iterate over the map and append each key to the keys slice and each value to the values slice.
We use two range-based for loops to iterate over the keys and values slices and print each key and value to the console using the fmt.Println function to verify that we have stored all keys and values 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 slices to store the keys and values
    var keys []string
    var values []int

    // Store keys and values separately
    for key, value := range myMap {
        keys = append(keys, key)
        values = append(values, value)
    }

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

    // Iterate over the values slice
    for _, value := range values {
        fmt.Println("Value:", value)
    }
}

Output

Key: one
Key: two
Key: three
Value: 1
Value: 2
Value: 3

3 Storing and Iterating Over Entries Separately

We can store entries in a separate slice and then iterate over the slice in Go, which provides a way to work with key-value pairs independently of 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 declare a slice named entries to store the key-value pairs from the map.
We use a range-based for loop to iterate over the map and append each key-value pair to the entries slice as a struct containing both the key and value.
We use another range-based for loop to iterate over the entries slice and print each key and value to the console using the fmt.Println function to verify that we have stored all entries separately.

Go Program

package main

import "fmt"

// Define a struct to store key-value pairs
type entry struct {
    key   string
    value int
}

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

    // Declare a slice to store the entries
    var entries []entry

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

    // Iterate over the entries slice
    for _, e := range entries {
        fmt.Println("Key:", e.key, "Value:", e.value)
    }
}

Output

Key: one Value: 1
Key: two Value: 2
Key: three Value: 3

Summary

In this tutorial, we learned How to Iterate Over Entries (Key-Value Pairs) in a Map in Go language with well detailed examples.

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How to Iterate Over Entries (Key-Value Pairs) in a Map in Go - Step by Step Examples