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How to Convert a Map to an Array of Keys in Go

How to Convert a Map to an Array of Keys in Go ?

Answer

To convert a map to an array of keys in Go, you can use a for loop to iterate over the map and store the keys in a slice. This provides a convenient way to extract all keys from the map.


✐ Examples

1 Converting a Map to an Array of Keys Using a for Loop

We can convert a map to an array of keys in Go using a for loop, which provides a straightforward way to iterate over all key-value pairs and collect the keys.

For example,

  1. 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.
  2. We declare a slice named keys to store the keys from the map.
  3. We use a for loop to iterate over the map and append each key to the keys slice using the append function.
  4. We print the keys to the console using a range-based for loop and the fmt.Println function to verify the conversion.

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

    // Convert map to an array of keys using a for loop
    for key := range myMap {
        keys = append(keys, key)
    }

    // Print the keys
    fmt.Println("Keys:", keys)
}

Output

Keys: [one two three]

2 Converting an Empty Map to an Array of Keys

We can also convert an empty map to an array of keys in Go using a for loop, which returns an empty slice when the map is empty.

For example,

  1. We start by declaring an empty map named emptyMap with string keys and integer values.
  2. We declare a slice named keys to store the keys from the map.
  3. We use a for loop to iterate over the empty map and append each key to the keys slice using the append function.
  4. We print the keys to the console using a range-based for loop and the fmt.Println function to verify that the slice is empty.

Go Program

package main

import "fmt"

func main() {
    // Declare an empty map
    emptyMap := make(map[string]int)

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

    // Convert empty map to an array of keys using a for loop
    for key := range emptyMap {
        keys = append(keys, key)
    }

    // Print the keys
    fmt.Println("Keys:", keys)
}

Output

Keys: []

3 Converting a Map to an Array of Keys After Adding Elements

We can convert a map to an array of keys in Go after adding elements using a for loop, which provides an updated slice of all keys in the map.

For example,

  1. We start by declaring an empty map named dynamicMap with string keys and integer values.
  2. We add some key-value pairs to the map using the map's index notation.
  3. We declare a slice named keys to store the keys from the map.
  4. We use a for loop to iterate over the map after adding elements and append each key to the keys slice using the append function.
  5. We print the keys to the console using a range-based for loop and the fmt.Println function to verify the updated list of keys.

Go Program

package main

import "fmt"

func main() {
    // Declare an empty map
    dynamicMap := make(map[string]int)

    // Add elements to the map
    dynamicMap["one"] = 1
    dynamicMap["two"] = 2
    dynamicMap["three"] = 3

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

    // Convert map to an array of keys using a for loop
    for key := range dynamicMap {
        keys = append(keys, key)
    }

    // Print the keys
    fmt.Println("Keys:", keys)
}

Output

Keys: [one two three]

Summary

In this tutorial, we learned How to Convert a Map to an Array of Keys in Go language with well detailed examples.


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