Question

This question has been bugging me for a while

Is it usual to have a piece of code that works like this:

bool failed = false;
if (ptr)
{
    if (ptr->value == foo)
    {
        print("error");
        failed = true;
    }
}
if (!failed)
{
    print("all systems go");
}

Or can it be done with out the bool?
I guess the first two ifs could be on one line but im not sure what order they are checked in different environments and I think it might make it harder to read.

Answer 1

All compilers should follow the same precedence order, so the check can be replace by this:

if (ptr && ptr->value == foo)
{
    print("error");
    failed = true;
}

If the first part (the lone ptr) is false, then the rest of the expression will not be evaluated. This is called short-circuiting.