nullptr vs. NULL: Why the C Shift to Type Safety?

nullptr vs NULL: Why the Replacement?

In C , the nullptr keyword has replaced NULL for pointer-based applications. While both options denote a null pointer, nullptr offers advantages that make it the preferred choice.

Why Use nullptr Over NULL?

The primary reason for replacing NULL with nullptr is type safety. NULL is a macro defined as (void )0, which has a type of (void ). This broad type compatibility can lead to unintentional behavior, particularly in scenarios involving overloaded functions.

For example, consider the following function declarations:

If you call f with a NULL pointer, the compiler may be unable to determine which function overload to execute. This is because NULL can be implicitly converted to a pointer type, allowing it to match the second overload.

Advantages of nullptr

nullptr, on the other hand, has a distinct type of std::nullptr_t. When used in overload resolution, it only matches instances of std::nullptr_t or pointer types. This eliminates the ambiguity caused by the broader type compatibility of NULL.

Furthermore, nullptr ensures that the intention to use a null pointer is clearly expressed in the code.

Therefore, using nullptr over NULL provides increased type safety, prevents unintentional behavior in overloaded function calls, and enhances code clarity.

The above is the detailed content of nullptr vs. NULL: Why the C Shift to Type Safety?. For more information, please follow other related articles on the PHP Chinese website!