Go Program to Reverse a String

Introduction

Reversing a string is a common operation in programming where the characters of the string are rearranged in reverse order. This guide will demonstrate how to write a Go program that takes a string as input and outputs the string reversed.

Problem Statement

Create a Go program that:

Prompts the user to enter a string.
Reverses the string.
Displays the reversed string.

Example:

Input: Hello
Output: olleH

Solution Steps

Import the fmt Package: Use import "fmt" to include the fmt package for formatted I/O operations.
Write the Main Function: Define the main function, which is the entry point of every Go program.
Input the String: Use fmt.Scanln to take input from the user for the string.
Reverse the String: Convert the string to a slice of runes and reverse the slice.
Display the Reversed String: Use fmt.Println to display the reversed string.

Go Program

package main

import "fmt"

/**
 * Go Program to Reverse a String
 * Author: https://www.javaguides.net/
 */
func main() {
    // Step 1: Declare a variable to hold the input string
    var input string

    // Step 2: Prompt the user to enter a string
    fmt.Print("Enter a string: ")
    fmt.Scanln(&input)

    // Step 3: Reverse the string by converting it to a slice of runes
    reversed := reverseString(input)

    // Step 4: Display the reversed string
    fmt.Println("Reversed string:", reversed)
}

// Function to reverse a string
func reverseString(s string) string {
    runes := []rune(s)
    for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
        runes[i], runes[j] = runes[j], runes[i]
    }
    return string(runes)
}

Explanation

Step 1: Declare Variables

The variable input is declared to store the user’s input string.

Step 2: Input the String

The program prompts the user to enter a string using fmt.Print. The fmt.Scanln function reads the input and stores it in the input variable.

Step 3: Reverse the String

The string is converted to a slice of runes to properly handle any Unicode characters. The function reverseString is used to reverse the slice by swapping elements from the start and end until the middle of the slice is reached.

Step 4: Display the Reversed String

The reversed slice of runes is converted back to a string and displayed using fmt.Println.

Reverse Function

The reverseString function takes a string, converts it into a slice of runes, and swaps the elements to reverse the order of the string. The final reversed string is returned to the caller.

Output Example

Example 1:

Enter a string: Hello
Reversed string: olleH

Example 2:

Enter a string: GoLang
Reversed string: gnaLoG

Conclusion

This Go program demonstrates how to reverse a string by converting it to a slice of runes, reversing the slice, and converting it back to a string. It covers basic programming concepts such as string manipulation, slices, and loops. This example is useful for beginners learning Go programming and understanding how to work with strings and slices in Go.