Should You Use `if (ptr == NULL)` or `if (ptr)` for Null Pointer Checks in C/C ?

What's the Best Way to Check for NULL Pointers in C/C ?

In a recent code review, a contributor asserted that all NULL pointer checks should be performed with an explicit comparison to NULL:

<code class="cpp">int * some_ptr;
// ...
if (some_ptr == NULL)
{
    // Handle null-pointer error
}
else
{
    // Proceed
}</code>

This approach was opposed by another reviewer, who argued that the traditional method of using a pointer variable in an if statement is also a valid and concise way to check for NULL:

<code class="cpp">int * some_ptr;
// ...
if (some_ptr)
{
    // Proceed
}
else
{
    // Handle null-pointer error
}</code>

. Which method do you prefer and why?

According to the preferred answer, the latter method is preferable for several reasons:

• Simplicity: The if (ptr) or if (!ptr) syntax is simple and intuitive.
• Compatibility with C classes: C classes such as unique_ptr and shared_ptr provide a conversion to bool that enables this idiom.
• Avoidance of errors due to accidental assignment: The == operator can lead to errors such as if (some_ptr = NULL), which can be difficult to find and debug.

In conclusion, when checking for NULL pointers in C/C , the preferred method is to use the idiomatic if (ptr) or if (!ptr) syntax. This approach is clear, concise, and compatible with C classes.

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