C Program to Check Whether a Number is Palindrome or Not

In this programming tutorial, we will develop a C program to determine whether a given number is a palindrome or not. A palindrome number remains the same when its digits are reversed. We will provide a step-by-step explanation of the algorithm, present the C code implementation, and include examples of the program’s output.

Algorithm for Checking Palindrome Number

1. Input: Accept an integer from the user.
2. Initialization: Set variables num to the input number, reversed to 0, and originalNum to num.
3. Loop:
   • In a loop, reverse the digits of the number by appending the last digit to reversed.
   • Update the value of num by removing its last digit using integer division (/).
   • Repeat the loop until num becomes 0.
4. Comparison: Compare originalNum with reversed.
   • If they are equal, the number is a palindrome.
   • Otherwise, it is not a palindrome.
5. Output: Display whether the number is a palindrome or not.

C Program for Checking Palindrome Number

#include <stdio.h>

int main() {
    int num, reversed = 0, originalNum;

    // Input an integer from the user
    printf("Enter an integer: ");
    scanf("%d", &num);

    // Save the original number
    originalNum = num;

    // Reverse the digits of the number
    while (num != 0) {
        reversed = reversed * 10 + num % 10;
        num /= 10;
    }

    // Check if the number is a palindrome
    if (originalNum == reversed) {
        printf("%d is a palindrome.\n", originalNum);
    } else {
        printf("%d is not a palindrome.\n", originalNum);
    }

    return 0;
}

Output Example

Example: Check Palindrome Number (e.g., 121)

Enter an integer: 121
121 is a palindrome.

Example: Check Non-Palindrome Number (e.g., 456)

Enter an integer: 456
456 is not a palindrome.

Explanation

1. Input: The user is prompted to enter an integer (e.g., 121).
2. Initialization: Variables num stores the input number, reversed is initialized to 0, and originalNum saves the original input.
3. Loop:
   • In each iteration of the loop, reversed is updated by appending the last digit of num.
   • The last digit is removed from num using integer division (/).
   • The loop continues until num becomes 0.
4. Comparison: The original number (originalNum) is compared with the reversed number (reversed).
   • If they are equal, the number is a palindrome.
   • Otherwise, it is not a palindrome.
5. Output: The program displays whether the input number is a palindrome or not.

Conclusion

This C program efficiently checks whether a given number is a palindrome or not by reversing its digits and comparing the reversed number with the original. Run the program with different numbers to observe the results. If you have any questions or need further clarification, please feel free to ask!