What does the comma operator , do?
What does the , operator do in C?
The expression:
(expression1, expression2)
First expression1 is evaluated, then expression2 is evaluated, and the value of expression2 is returned for the whole expression.
I've seen used most in while loops:
string s;
while(read_string(s), s.len() > 5)
{
//do something
}
It will do the operation, then do a test based on a side-effect. The other way would be to do it like this:
string s;
read_string(s);
while(s.len() > 5)
{
//do something
read_string(s);
}