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palindrome program in C

In this program, You will learn how to check number is palindrome or not, using a while loop, or do a while loop.

a number is a palindrome if the reversed number is equal to the original number. for example 121, 101, 12321 are palindrome numbers.

Palindrome in C using while loop

#include<stdio.h>
int main()
{
  int r,n,rev=0,copy;
  printf(" \n enter the number:");
  scanf("%d",&n);
  copy=n;
  while(n>0)
  { 
    /*It will find the reverse of the input entered by the user.*/
    rev=rev*10+n%10;
    n=n/10;
  }
  // Compare the reverse of input with the temporary variable
  if(copy==rev)
    printf("\n %d is palindrom a number",copy);
  else
    printf("\n %d is not a palindrome number",copy);
  return 0;
}

output

enter the number:121
121 is a palindrom number
enter the number:123
123 is not a palindrome number

Palindrome in C using do while loop

#include<stdio.h>
int main()
{
  int r,n,rev=0,copy;
  printf(" \n enter the number:");
  scanf("%d",&n);
  copy=n;
  do{   
    /*it will revese number */
    rev=rev*10+n%10;
    n=n/10;
    }
  while(n>0);
  if(copy==rev)
    printf("\n %d is a palindrom number",copy);
  else
    printf("\n %d is not a palindrome number",copy);
    return 0;
}

output

enter the number:121
121 is a palindrom number
enter the number:123
123 is not a palindrome number

working of palindrome number

In the above program, asked the user to enter a positive number which is store in the variable n
The number is saved into another variable copy to check it when we need to compare our original number with reverse number
Inside the loop, one by one last digit number is separated using code n%10 and rev*10 will maintain their n^th position
After reversing the digits, compare a reverse value with the original value which is store in the copy variable
If the numbers are equal, then the number is a palindrome, otherwise, it's not.

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