Go Program to Delete a Key from a Map

Introduction

In Go, maps are collections of key-value pairs where each key is unique. You can delete a key (and its associated value) from a map using the delete function. This guide will demonstrate how to delete a key from a map in Go.

Problem Statement

Create a Go program that:

Declares and initializes a map with some key-value pairs.
Deletes a specified key from the map.
Displays the map before and after deleting the key.

Example:

Input: Map: {"Apple": 5, "Banana": 3, "Cherry": 7}, Key to delete: "Banana"

Output:

Map before deletion: map[Apple:5 Banana:3 Cherry:7]
Map after deletion: map[Apple:5 Cherry:7]

Solution Steps

Import the fmt Package: Use import "fmt" for formatted I/O operations.
Write the Main Function: Define the main function, which is the entry point of every Go program.
Create and Initialize the Map: Use a map literal to create and initialize a map with some key-value pairs.
Delete a Key from the Map: Use the delete function to remove the specified key from the map.
Display the Map: Use fmt.Println to display the map before and after deleting the key.

Go Program

package main

import "fmt"

/**
 * Go Program to Delete a Key from a Map
 * Author: https://www.javaguides.net/
 */
func main() {
    // Step 1: Create and initialize the map
    fruitMap := map[string]int{
        "Apple":  5,
        "Banana": 3,
        "Cherry": 7,
    }

    // Display the map before deletion
    fmt.Println("Map before deletion:", fruitMap)

    // Step 2: Delete the specified key from the map
    delete(fruitMap, "Banana")

    // Step 3: Display the map after deletion
    fmt.Println("Map after deletion:", fruitMap)
}

Explanation

Step 1: Create and Initialize the Map

The map is created and initialized using a map literal. For example, fruitMap := map[string]int{"Apple": 5, "Banana": 3, "Cherry": 7} creates a map with three key-value pairs.

Step 2: Delete the Specified Key from the Map

The delete function is used to remove a key from the map. The syntax delete(map, key) is used. For example, delete(fruitMap, "Banana") removes the key "Banana" and its associated value from the map.

Step 3: Display the Map

The program prints the map using fmt.Println to display its contents before and after the key has been deleted.

Output Example

Example 1:

Map before deletion: map[Apple:5 Banana:3 Cherry:7]
Map after deletion: map[Apple:5 Cherry:7]

Example 2:

If you try to delete a key that doesn’t exist:

delete(fruitMap, "Mango") // "Mango" does not exist in the map
fmt.Println("Map after attempting to delete non-existent key:", fruitMap)

Output:

Map after attempting to delete non-existent key: map[Apple:5 Banana:3 Cherry:7]

Example 3:

Starting with a larger map:

fruitMap := map[string]int{
    "Apple":  5,
    "Banana": 3,
    "Cherry": 7,
    "Mango":  10,
    "Orange": 8,
}
delete(fruitMap, "Mango")
fmt.Println("Map after deleting 'Mango':", fruitMap)