why this two strings are not equal

Question

#include <iostream>
#include <string>
using namespace std;

int isPalindrome(string x){
string res;
for (int i = x.size(); i >= 0; i--){
res += x[i];
}
cout << x.compare(res) << endl;
return res==x ? 1 : 0;
}

int main() {
string num;
cin >> num;
printf("%d",isPalindrome(num));
return 0;
}

when I enter a string like "8888" the output is that is not a palindrome...
but the strings are really equal...
could you tell me why my code doesn't work?

Answer 1

Try,,, x.size() - 1.

Answer 2

Read this ...

Returns a signed integral indicating the relation between the strings:
value relation between compared string and comparing string
0 They compare equal
<0 Either the value of the first character that does not match is lower in the compared string, or all compared characters match but the compared string is shorter.
>0 Either the value of the first character that does not match is greater in the compared string, or all compared characters match but the compared string is longer.

Answer 3

Thanks! rodwynnejones