C Exercises: Check whether an integer is a palindrome or not

Last update on March 20 2025 12:36:18 (UTC/GMT +8 hours)

2. Palindrome Integer Check Variants

Write a C program to check whether an integer is a palindrome or not. An integer is a palindrome when it reads the same forward as backward.

Example:
Input:
i = 1221
i = -121
i = 100
Output:
Is Palindrome: 1
Is Palindrome: 0
Is Palindrome: 0

Visual Presentation:

Sample Solution:

C Code:

#include <stdio.h>
#include <stdbool.h>

// Function to check if a number is a palindrome
bool is_Palindrome(int i) {
    int n, d, y = 0;

    // Check if the number is negative; negative numbers cannot be palindromes
    if (i < 0) 
        return false;

    n = i;
    // Reverse the number and compare it with the original number
    while (n) {
        d = n % 10;

        // Check for potential overflow
        if (y > (0x7fffffff - d) / 10) 
            return false;   // Return false if overflow is detected

        y = y * 10 + d;  // Reverse the number
        n = n / 10;      // Move to the next digit
    }

    return (y == i);  // Return true if the reversed number is equal to the original number
}

int main(void)
{
    int i = 1221;
    printf("Original integer: %d  ", i);
    printf("\nIs Palindrome: %d  ", is_Palindrome(i));

    i = -121;
    printf("\nOriginal integer: %d  ", i);
    printf("\nIs Palindrome: %d  ", is_Palindrome(i));

    i = 100;
    printf("\nOriginal integer: %d  ", i);
    printf("\nIs Palindrome: %d  ", is_Palindrome(i));

    return 0;
}

Sample Output:

Original integer: 1221  
Is Palindrome: 1  
Original integer: -121  
Is Palindrome: 0  
Original integer: 100  
Is Palindrome: 0  

Flowchart:

For more Practice: Solve these Related Problems:

• Write a C program to determine if an integer is a palindrome by comparing its digit array without converting to a string.
• Write a C program to check palindromic property of an integer using arithmetic operations only.
• Write a C program to test palindrome property while ignoring the sign and any trailing zeros.
• Write a C program to verify the palindrome property of an integer by reversing half of its digits and comparing.

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