Question

I’ve been wondering, if i have a function like:

bool Foo::Bar()
{
     return A() || B() || C();
}

If A() returns true, would Bar() imediately return true or would it still calculate the results of B() and C() before evaluating the final value?

Answer 1

If A() is true, neither B nor C will be evaluated. This is called operator short-circuiting.

Similarly, in a statement such as A && B && C, if A is false, neither B or C will be evaluated.

This is not just an optimization; it is especially useful when B or C depend on A. For example, you can both test that a pointer points to something and invoke a method on the object being pointed to in a single statement:

if (my_pointer && my_pointer->some_method() > 9) {

}