What does the comma operator do?
Solution 1:
Comma operator is applied and the value 5 is used to determine the conditional's true/false.
It will execute blah() and get something back (presumably), then the comma operator is employed and 5 will be the only thing that is used to determine the true/false value for the expression.
Note that the , operator could be overloaded for the return type of the blah() function (which wasn't specified), making the result non-obvious.
Solution 2:
If the comma operator is not overloaded, the code is similar to this:
blah();
if (5) {
// do something
}
If the comma operator is overloaded, the result will be based on that function.
#include <iostream>
#include <string>
using namespace std;
string blah()
{
return "blah";
}
bool operator,(const string& key, const int& val) {
return false;
}
int main (int argc, char * const argv[]) {
if (blah(), 5) {
cout << "if block";
} else {
cout << "else block";
}
return 0;
}
(edited to show comma operator overloading scenario. thanks to David Pierre for commenting on this)
Solution 3:
I know one thing that this kind of code should do: it should get the coder fired. I would be quite a bit afraid to work next to someone who writes like this.