Should You Explicitly Check for NULL Pointers in C/C ?

Checking for NULL Pointers in C/C : Comparison of Methods

In code reviews, the topic of NULL pointer checking often arises. One contributor advocates for using explicit comparisons with NULL:

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

Another party believes that implicitly checking for NULL by using the pointer variable in an if statement is equally clear:

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

This latter method is preferred for several reasons. Firstly, it avoids the risk of introducing logical errors such as assigning NULL to the pointer variable instead of comparing it:

if (some_ptr = NULL)

Secondly, it is compatible with C classes like unique_ptr, shared_ptr, and auto_ptr that act as pointers but provide conversions to boolean. An explicit comparison to NULL would require a conversion to a pointer, which may have side effects or be less efficient.

Explicit comparisons to NULL are unnecessarily verbose and introduce potential confusion. The C language explicitly states that non-zero values in boolean contexts are true, and zero values are false. Using implicit checks for NULL is clear and concise, expressing the intent of the code without redundant specificity.

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