Creating a function to check if a number is Palindrome - c

Question

i am trying to make a function to return true if the number is palindrome and return false if the number is not , so first i created a function that reverse the number then another function to tell if the reversed number is equal to the original number , but it not returning for me the correct output , any help ?
#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <math.h>
//Reversing a number
int DigitsReversing(int num)
{
int resultofR = 0;
while (num > 0)
{
resultofR = resultofR * 10 + num % 10;
num = num / 10;
}
return resultofR;
}
//telling if the original number equal to the reversed number if yes return if not return false
int isPali(int num)
{
DigitsReversing(num);
int resultofR;
if (num == resultofR)
return true;
else
return false;
return 0;
}
//calling the function
int main()
{
int num;
scanf("%d", &num);
printf("%d", isPali(num));
return 0;
}
edited **** :
#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <math.h>
#include <stdbool.h>
int DigitsReversing(int num)
{
int resultofR = 0;
while (num > 0)
{
resultofR = resultofR * 10 + num % 10;
num = num / 10;
}
return resultofR;
}
bool isPali(int num , int resultofR)
{
resultofR = DigitsReversing(num);
if (num == resultofR)
return true;
else
return false;
}
int main()
{
int num, resultofR;
scanf("%d", &num);
resultofR = DigitsReversing(num);
isPali(num, resultofR);

Answer 1

C does have a boolean datatype. Usually, 0 is false and 1 is true. They return value 1 for true and 0 for false.
As #exnihilo and #bob__ suggested C does have boolean datatypes.
#include<stdio.h>
#include<math.h>
//Reversing a number
int DigitsReversing(int num)
{
int resultofR = 0;
while (num > 0)
{
resultofR = resultofR * 10 + num % 10;
num = num / 10;
}
return resultofR;
}
//telling if the original number equal to the reversed number if yes return if not return false
void isPali(int num)
{
int resultofR= DigitsReversing(num);
if (num == resultofR)
printf("True");
else
printf("False");
}
//calling the function
int main()
{
int num;
scanf("%d",&num);
isPali(num);
return 0;
}
OUTPUT
For non-palindrome numbers.
9998
False
--------------------------------
Process exited after 10.35 seconds with return value 0
Press any key to continue . . .
For palindrome numbers.
9999
True
--------------------------------
Process exited after 10.35 seconds with return value 0
Press any key to continue . . .

Answer 2

The posted snippets show some confusion about fundamental topics like the correct way to pass arguments to a function and collect the returned value or just the differnece between an "output" and a "returned" value.
Consider this, for example:
bool isPali(int num , int resultofR)
{ // ^^^^^^^^^ It's passed to the function...
resultofR = DigitsReversing(num); // <- and immediately overwritten by another value
if (num == resultofR)
return true;
else
return false;
}
int main()
{
int resultofR;
// ...
resultofR = DigitsReversing(num); // <-- This is effectually called twice
isPali(num, resultofR); // <-- The returned value is ignored
}
You just need to write one function
#include <stdbool.h>
bool is_palindrome(long num)
{
long reversed = 0;
for (long i = num; i > 0; i /= 10)
{
reversed = reversed * 10 + i % 10;
}
return reversed == num;
}
Then, call it and interpret its return value properly, to generate the wanted output
int number;
scanf("%d", &number);
printf("%s\n", is_palindrome(number) ? "True" : "False");