Why this always return true?

Question

#include <iostream>
using namespace std;

bool isPalindrome(int x) {
int z=x;
int inv=0;
while(x>0){
inv=inv*10;
inv= inv+x%10;
x=x/10;
}
if(x=inv){
return true;
}
else{
return false;
}
}

Answer 1

"x = inv" means you're assigning to x the value of inv, it is not a comparison. The return value of this kind of expression is always the value you're assigning, meaning the only case it can return false is when x = 0, so that "x = inv" results in 0. To make this work simply substitute "x = inv" with "x == inv".

Answer 2

Just an additional note to notice

I saw you copied <x> to <z> and I thought you did it to preserve <x> value cause <x> will be compared against <inv> to decide the function's return value.

The while...loop should use <z> instead of <x>.. We don't want <x> value to change.

while( z )
{
inv = inv * 10 + z % 10;
z /= 10;
}

Answer 3

Yes i noticed it, i changed after it returned always true

Answer 4

Thanks