Checking for NULL pointer in C/C++

user_34731 0
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In a recent code review, a contributor is trying to enforce that all NULL checks on pointers be performed in the following manner:

int * some_ptr;
// ...
if (some_ptr == NULL)
{
    // Handle null-pointer error
}
else
{
    // Proceed
}

instead of

int * some_ptr;
// ...
if (some_ptr)
{
    // Proceed
}
else
{
    // Handle null-pointer error
}

I agree that his way is a little more clear in the sense that it's explicitly saying "Make sure this pointer is not NULL", but I would counter that by saying that anyone who's working on this code would understand that using a pointer variable in an if statement is implicitly checking for NULL. Also I feel the second method has a smaller chance of introducing a bug of the ilk:

if (some_ptr = NULL)

which is just an absolute pain to find and debug.

Which way do you prefer and why?

if-statement coding-style null c c++
14 Answers

Just one more point in favor of the foo == NULL practice: If foo is, say, an int * or a bool *, then the if (foo) check can accidentally be interpreted by a reader as testing the value of the pointee, i.e. as if (*foo). The NULL comparison here is a reminder that we're talking about a pointer.

But I suppose a good naming convention makes this argument moot.

user_2232670
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