Go – Reverse a Number

In this tutorial, we will learn how to reverse a number using the Go programming language (Golang). Reversing a number involves rearranging its digits in reverse order. This task demonstrates the use of loops, arithmetic operators, and conditionals in Go. We will provide a step-by-step explanation and a program to achieve this functionality.

Logic to Reverse a Number

The logic to reverse a number involves extracting its digits and rearranging them in reverse order:

  1. Extract the Last Digit: Use the modulus operator (%) to get the last digit of the number.
  2. Build the Reversed Number: Multiply the reversed number by 10 and add the extracted digit to it.
  3. Remove the Last Digit: Use integer division (/) to remove the last digit of the original number.
  4. Repeat: Continue the process until all digits of the number are reversed.

Example Program to Reverse a Number

Program – reverse_number.go

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package main

import "fmt"

func main() {
    // Declare a variable to hold the input number
    var num int

    // Prompt the user to enter a number
    fmt.Print("Enter an integer: ")
    fmt.Scan(&num)

    // Initialize a variable to store the reversed number
    reversed := 0

    // Store the original number for display
    original := num

    // Reverse the number
    for num != 0 {
        digit := num % 10         // Extract the last digit
        reversed = reversed*10 + digit // Build the reversed number
        num /= 10                 // Remove the last digit
    }

    // Display the reversed number
    fmt.Printf("The reverse of %d is %d\n", original, reversed)
}

Explanation of Program

  1. Declare Variables: Two integer variables are declared. num stores the user input, and reversed is initialized to 0 to store the reversed number.
  2. Prompt the User: The program prompts the user to enter an integer using the fmt.Print function.
  3. Extract and Reverse Digits: A loop is used to extract each digit of the number using the modulus operator (%). The digits are added to reversed, multiplied by 10 to shift the digits left.
  4. Remove Last Digit: The number is divided by 10 in each iteration to remove the last digit.
  5. Display the Result: The reversed number is displayed using fmt.Printf, along with the original number for reference.

Output

This program successfully reverses the digits of a number by iteratively extracting and rearranging its digits.