C Program to Check Whether a Number is Palindrome or Not

This C program checks whether a given number is a palindrome or not.

What is a Palindrome?

A palindrome is a sequence of characters, numbers, or other elements that reads the same forward and backward. In the context of numbers, a palindrome number is a number that remains the same when its digits are reversed. you can easily determine whether a number is a palindrome or not. Palindrome numbers can be interesting to study and are often used in programming challenges and interview questions.

Problem Statement

Write a C program that checks whether a given number is a palindrome or not.

A palindrome number is a number that remains the same when its digits are reversed.

Ensure that your program handles both positive and negative numbers correctly.

C Program to Check Whether a Number is Palindrome or Not

#include <stdio.h>

int isPalindrome(int number)
{
    int reverse = 0;
    int original = number;

    while (number != 0)
    {
        int remainder = number % 10;
        reverse = reverse * 10 + remainder;
        number /= 10;
    }

    if (original == reverse)
        return 1;
    else
        return 0;
}

int main()
{
    int number;

    printf("Enter a number: ");
    scanf("%d", &number);

    if (isPalindrome(number))
        printf("%d is a palindrome.\n", number);
    else
        printf("%d is not a palindrome.\n", number);

    return 0;
}

How it Works

1. The program starts by prompting the user to enter a number.
2. The input number is read from the user and stored in the variable number.
3. The program then calls the isPalindrome function with the input number as an argument.
4. Inside the isPalindrome function:
   • Two variables, reverse and original, are initialized to 0 and original = number, respectively.
   • A loop is used to reverse the digits of the number:
     • The last digit of the number is extracted using the modulo operator (remainder = number % 10).
     • The reverse variable is updated by multiplying it by 10 and adding the remainder.
     • The number is divided by 10 to remove the last digit (number /= 10).
     • These steps are repeated until the number becomes 0.
   • After the loop, the reverse and original variables are compared.
   • If they are equal, the function returns 1 to indicate that the number is a palindrome.
   • If they are not equal, the function returns 0 to indicate that the number is not a palindrome.
5. The result of the isPalindrome function is stored in a variable called isPal.
6. The program then displays the appropriate message based on the value of isPal:
   • If isPal is 1, the program prints “<number> is a palindrome.”
   • If isPal is 0, the program prints “<number> is not a palindrome.”

That’s how the program works! It checks whether a given number is a palindrome by reversing its digits and comparing the reversed number with the original number.

Input / Output