C program to find palindrome number by using while loop

Palindrome number is a number which remains same when it reverses. In C language, the user is allowed to enter any positive integer and to check, whether the given number is palindrome number or not by using the while loop.

Example1

Following is the C Program to find Palindrome number by using the while loop −

 Live Demo

#include <stdio.h>
int main(){
   int num, temp, rem, rev = 0;
   printf("enter a number:
");
   scanf("%d", &num);
   temp = num;
   while ( temp > 0){
      rem = temp %10;
      rev = rev *10+ rem;
      temp = temp /10;
   }
   printf("reversed number is = %d
", rev);
   if ( num == rev )
      printf("
%d is Palindrome Number.
", num);
   else
      printf("%d is not the Palindrome Number.
", num);
   return 0;
}

Output

When the above program is executed, it produces the following result −

enter a number:
1234
reversed number is = 4321
1234 is not the Palindrome Number.
enter a number:
1221
reversed number is = 1221
1221 is Palindrome Number.

Example2

Consider another example for the C program to find palindrome number by using the while loop for strings.

 Live Demo

#include <stdio.h>
#include <string.h>
void pal(char string[]);
int main(){
   char string[100];
   printf("enter a string: ");
   gets(string);
   pal(string);
   return 0;
}
void pal(char string[]){
   int i = 0;
   int length = strlen(string) - 1;
   while (length > i){
      if(string[i++] != string[length--]){
         printf("
 %s is not a palindrome", string);
         return;
      }
   }
   printf("
 %s is a palindrome string", string);
}

Output

When the above program is executed, it produces the following result −

enter a string: tutorial
tutorial is not a palindrome
enter a string: saas
saas is a palindrome string