Go Program to Add Key-Value Pairs to a Map

Introduction

In Go, maps are collections of key-value pairs where each key is unique. You can dynamically add key-value pairs to a map, even after it has been created and initialized. This guide will demonstrate how to add key-value pairs to a map in Go.

Problem Statement

Create a Go program that:

Declares and initializes an empty map.
Adds key-value pairs to the map.
Displays the map after adding the key-value pairs.

Example:

Input: Key-Value pairs to add: {"Apple": 5, "Banana": 3, "Cherry": 7}
Output: Map content: {"Apple": 5, "Banana": 3, "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 an Empty Map: Use the make function to create an empty map.
Add Key-Value Pairs to the Map: Use the syntax map[key] = value to add key-value pairs to the map.
Display the Map: Use fmt.Println to display the map after adding the key-value pairs.

Go Program

package main

import "fmt"

/**
 * Go Program to Add Key-Value Pairs to a Map
 * Author: https://www.javaguides.net/
 */
func main() {
    // Step 1: Create and initialize an empty map
    fruitMap := make(map[string]int)

    // Step 2: Add key-value pairs to the map
    fruitMap["Apple"] = 5
    fruitMap["Banana"] = 3
    fruitMap["Cherry"] = 7

    // Step 3: Display the map after adding the key-value pairs
    fmt.Println("Map content:", fruitMap)
}

Explanation

Step 1: Create and Initialize an Empty Map

The make function is used to create an empty map. For example, fruitMap := make(map[string]int) creates an empty map where the keys are strings representing fruit names, and the values are integers representing quantities.

Step 2: Add Key-Value Pairs to the Map

Key-value pairs are added to the map using the syntax map[key] = value. For example, fruitMap["Apple"] = 5 adds the key "Apple" with the value 5 to the map.

Step 3: Display the Map

The program prints the map using fmt.Println to display its contents after the key-value pairs have been added.

Output Example

Example 1:

Map content: map[Apple:5 Banana:3 Cherry:7]

Example 2:

Adding more key-value pairs:

fruitMap["Mango"] = 10
fruitMap["Orange"] = 8
fmt.Println("Map content:", fruitMap)

Output:

Map content: map[Apple:5 Banana:3 Cherry:7 Mango:10 Orange:8]

Example 3:

Starting with an empty map and adding a single key-value pair:

fruitMap := make(map[string]int)
fruitMap["Grape"] = 12
fmt.Println("Map content:", fruitMap)