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Print all palindrome numbers in a given range

Introduction

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

 Examples:

  • 121 → palindrome
  • 12321 → palindrome
  • 123 → not a palindrome

This program prints all palindrome numbers in a given range using a for, while and do..while loop.

 

C Program: Print all palindrome numbers in a given range

Method 1: Using for loop

C 
#include <stdio.h>


 


int main() {


    int start, end, num, reversed, remainder, original;


 


    // Input


    printf("Enter the starting number of the range: ");


    scanf("%d", &start);


    printf("Enter the ending number of the range: ");


    scanf("%d", &end);


 


    // Validate input


    if (start > end || start < 0) {


        printf("Invalid range!\n");


        return 1;


    }


 


    printf("Palindrome numbers between %d and %d are:\n", start, end);


 


    // Loop through the range


    for (num = start; num <= end; num++) {


        original = num;


        reversed = 0;


 


        // Reverse the number


        for (int temp = num; temp != 0; temp /= 10) {


            remainder = temp % 10;


            reversed = reversed * 10 + remainder;


        }


 


        // Check if palindrome


        if (reversed == original)


            printf("%d ", num);


    }


 


    printf("\n");


    return 0;


}

Output

 
OUTPUT 1 :
Enter the starting number of the range: 100
Enter the ending number of the range: 150
Palindrome numbers between 100 and 150 are:
101 111 121 131 141

OUTPUT 2 :
Enter the starting number of the range: 1
Enter the ending number of the range: 20
Palindrome numbers between 1 and 20 are:
1 2 3 4 5 6 7 8 9 11

Explanation

  1. User inputs the start and end of the range.
  2. Outer for loop iterates each number in the range.
  3. For each number:
    • Reverse the number using another for
    • Compare the reversed number with the original.
  4. If equal → print the number as palindrome.

 

C Program: Print all palindrome numbers in a given range

Method 2: Using while loop

C 
#include <stdio.h>


 


int main() {


    int start, end, num, original, reversed, remainder, temp;


 


    // Input


    printf("Enter the starting number of the range: ");


    scanf("%d", &start);


    printf("Enter the ending number of the range: ");


    scanf("%d", &end);


 


    // Validate input


    if (start > end || start < 0) {


        printf("Invalid range!\n");


        return 1;


    }


 


    printf("Palindrome numbers between %d and %d are:\n", start, end);


 


    num = start;


    while (num <= end) {


        original = num;


        reversed = 0;


        temp = num;


 


        // Reverse the number


        while (temp != 0) {


            remainder = temp % 10;


            reversed = reversed * 10 + remainder;


            temp /= 10;


        }


 


        // Check if palindrome


        if (reversed == original)


            printf("%d ", num);


 


        num++;


    }


 


    printf("\n");


    return 0;


}

Output

 
OUTPUT 1 :
Enter the starting number of the range: 100
Enter the ending number of the range: 150
Palindrome numbers between 100 and 150 are:
101 111 121 131 141

OUTPUT 2 :
Enter the starting number of the range: 1
Enter the ending number of the range: 20
Palindrome numbers between 1 and 20 are:
1 2 3 4 5 6 7 8 9 11

Explanation

  1. User enters the start and end of the range.
  2. Outer while loop iterates each number from start to end.
  3. For each number:
    • Reverse the number using an inner while
    • Compare the reversed number with the original.
  4. If equal → print the number as palindrome.

 

C Program: Print all palindrome numbers in a given range

Method 3: Using do..while loop

C 
#include <stdio.h>


 


int main() {


    int start, end, num, original, reversed, remainder, temp;


 


    // Input


    printf("Enter the starting number of the range: ");


    scanf("%d", &start);


    printf("Enter the ending number of the range: ");


    scanf("%d", &end);


 


    // Validate input


    if (start > end || start < 0) {


        printf("Invalid range!\n");


        return 1;


    }


 


    printf("Palindrome numbers between %d and %d are:\n", start, end);


 


    num = start;


    if (num <= end) {


        do {


            original = num;


            reversed = 0;


            temp = num;


 


            // Reverse the number using do...while


            if (temp == 0)


                reversed = 0; // special case for 0


            else


                do {


                    remainder = temp % 10;


                    reversed = reversed * 10 + remainder;


                    temp /= 10;


                } while (temp != 0);


 


            // Check if palindrome


            if (reversed == original)


                printf("%d ", num);


 


            num++;


        } while (num <= end);


    }


 


    printf("\n");


    return 0;


}

Output

 
OUTPUT 1 :
Enter the starting number of the range: 100
Enter the ending number of the range: 150
Palindrome numbers between 100 and 150 are:
101 111 121 131 141

OUTPUT 2 :
Enter the starting number of the range: 1
Enter the ending number of the range: 20
Palindrome numbers between 1 and 20 are:
1 2 3 4 5 6 7 8 9 11

Explanation

  1. User enters the start and end of the range.
  2. Outer do..while loop iterates num from start to end.
  3. For each number:
    • Inner do..while loop reverses the number.
    • Compare reversed number with the original.
  4. If equal → print the number as palindrome.
  5. Ensures that even the first number in the range is checked at least once.

 

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