Check whether the given number is Palindrome or Not

Palindrome numbers will remain the same when it’s digits are reversed.

Like, 99,121,323,505 etc



Example

Case 1

num = 121

after digits’ reversal

reverse of num = 121

Output:

Palindrome (121 == 121)

Case 2

num = 345

after digits’ reversal

reverse of num = 543

Output:

Not Palindrome (345 != 543)



Logic

Previous tutorial, we know how to reverse a number

Just apply the concept here.


Get a number from user

Reverse the number

If both number and reversed number are equal

     Print “Palindrome Number”

Else

     Print “Non-Palindrome Number”

Important thing to note in reversing a number is, after the loop execution the value of num becomes zero.

Because each time we are dividing num by 10.

Pictorial Explanation

Number becomes zero

So, num will be always zero after the process. So, we have to copy the num value to another variable for further checking.



Palindrome Number

num = 121

Pictorial Explanation

Palindrome number



Non-Palindrome Number

num = 123

Pictorial Explanation

Non-palindrome Number



Program

Example

#include<stdio.h>

int main()
{
    //variable ans will have the reversed number
    int num, ans = 0,copy;
    
    //get input from user
    scanf("%d",&num);
    
    //assigning num value to variable copy for checking
    //Because after while loop num value becomes zero.
    copy = num;
    
    //do till num > 0
    while(num > 0)
    {
        //split the last digit 
        int mod = num % 10;
        
        //multiply ans with 10 and add the splitted digit
        ans = ans * 10 + mod;
        
        //divide num by 10
        num = num / 10;
    }
    
    //if both reversed and original number are equal, print palindrome
    
    if(ans == copy)
           printf("Palindrome\n");
    else
           printf("Non-Palindrome\n"); //otherwise print non-palindrome
    
    return 0;
}