Is it Safe to Check for Non-Null Pointers with `if(pointer)` Instead of `if(pointer != NULL)`?

Checking for Non-Null Pointers: if(pointer) vs. if(pointer != NULL)

Question:

Is it acceptable to verify a pointer's non-null status using if(pointer) instead of the conventional if(pointer != NULL)?

Answer:

Yes, this is permissible. Using if(pointer) is safe because the null pointer is implicitly converted to the boolean value false, while non-null pointers are converted to true. This behavior is defined in the C 11 standard under the section on Boolean Conversions:

"A prvalue of arithmetic, unscoped enumeration, pointer, or pointer to member type can be converted to a prvalue of type bool. A zero value, null pointer value, or null member pointer value is converted to false; any other value is converted to true. A prvalue of type std::nullptr_t can be converted to a prvalue of type bool; the resulting value is false."

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