Go Program to Find the Length of a Map

Introduction

In Go, maps are collections of key-value pairs where each key is unique. You can find the length of a map, which is the number of key-value pairs it contains, using the len function. This guide will demonstrate how to find the length of a map in Go.

Problem Statement

Create a Go program that:

Declares and initializes a map with some key-value pairs.
Finds and displays the length of the map.

Example:

Input: Map: {"Apple": 5, "Banana": 3, "Cherry": 7}
Output: Length of the map: 3

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.
Find the Length of the Map: Use the len function to find the number of key-value pairs in the map.
Display the Length of the Map: Use fmt.Println to display the length of the map.

Go Program

package main

import "fmt"

/**
 * Go Program to Find the Length of 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,
    }

    // Step 2: Find the length of the map using the len function
    length := len(fruitMap)

    // Step 3: Display the length of the map
    fmt.Printf("Length of the map: %d\n", length)
}

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: Find the Length of the Map

The len function is used to find the number of key-value pairs in the map. For example, length := len(fruitMap) stores the length of the map in the length variable.

Step 3: Display the Length of the Map

The program prints the length of the map using fmt.Printf to display the result in a formatted manner.

Output Example

Example 1:

Length of the map: 3

Example 2:

If the map is empty:

fruitMap := map[string]int{}
length := len(fruitMap)
fmt.Printf("Length of the map: %d\n", length)

Output:

Length of the map: 0

Example 3:

With a larger map:

fruitMap := map[string]int{
    "Apple":  5,
    "Banana": 3,
    "Cherry": 7,
    "Mango":  10,
    "Orange": 8,
}
length := len(fruitMap)
fmt.Printf("Length of the map: %d\n", length)