Performance warning for isspace function, conversion from int to bool - c++

Question

#include <iostream>
#include <algorithm>
#include <vector>
#include <string>
#include <iterator>
using namespace std;
bool notSpace(char c) {
return !isspace(c);
}
bool isSpace(char c) {
return isspace(c);
}
vector<string> split(const string& s) {
vector<string> words;
string::const_iterator i = s.begin();
while (i != s.end()) {
i = find_if(i, s.end(), notSpace); // " "
if (i != s.end()) {
string::const_iterator j = i;
j = find_if(i, s.end(), isSpace);
words.push_back(string(i, j));
i = j;
}
}
return words;
}
int main() {
string test = "Hello world, I'm a simple guy";
vector<string> words = split(test);
for (vector<string>::size_type i = 0; i < words.size();i++) {
cout << words[i] << endl;
}
return 0;
}
When I compile the code I get this warning:
warning C4800: 'int': forcing value to bool 'true' or 'false'
(performance warning)
on the return of this function:
bool isSpace(char c) {
return isspace(c);
}
Is good habit changing isspace(c) to (isspace(c) != 0) ? Or is it just an unnecessary fussiness?

Answer 1

Take a look at the code below:
#include <iostream>
using namespace std;
bool f()
{
return 2;
}
int main()
{
cout <<f()<<endl;
return 0;
}
it will print 1 when you return 2, that's why you get the warning.
someone may think a bool is kind of small integer, but it isn't.
If you go back to C, there was no bool type, that's why many C methods (like isspace) returns int, even WINDOWS type of BOOL is actually kind of integer and can return other values but TRUE (1) or FALSE (0).