CODEWITHSUNDEEP
c++for-loopcomma-operator
user12945091
user12945091

Reputation:

C++ for with multiple control statements using comma operator

How does comma operator if it is used in a 'for loop' for writing multiple control statements? i tried 

#include <iostream>

using namespace std;

int main() {
        for (int x = 0, y = 0; x < 3, y < 4; ++x, ++y) {
                cout << x << " " << y << endl;
        }
        return 0;
}

and it seems like only the last expression is evaluated. Ty

Upvotes: 1

Views: 249

Answers (1)

songyuanyao
songyuanyao

Reputation: 172964

This is how comma operator works. Its 1st operand x < 3 is evaluated, then the result is discarded; then the 2nd operand y < 4 is evaluated and the value is returned as the return value of the comma operator. x < 3 has not any effects here.

You might want to use operator&& or operator|| for this case, e.g. x < 3 && y < 4 or x < 3 || y < 4 based on your intent.

Upvotes: 5

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