Question

If I have an if statement in C that looks like:

if( function1() > 0 && function2() > 0 ){

    //blah

}

Which function will execute first and will it always execute in that order?

Answer 1

Here function1() is guaranteed to execute first.

The && operator is a short-circuiting operator. function2() won’t even be called unless the result of function1() is greater than zero.

From the C99 standard:

Unlike the bitwise binary & operator, the && operator guarantees left-to-right evaluation;
there is a sequence point after the evaluation of the first operand. If the first operand
compares equal to 0, the second operand is not evaluated.