C Casting: When Should I Use `reinterpret_cast` vs. `static_cast` for void* Conversions?

Deciding Between reinterpret_cast and static_cast

When working with C casting, it's crucial to understand the distinctions between reinterpret_cast and static_cast.

The Difference

• static_cast: Use for transformations that are valid at compile-time and preserve type information. It's the compiler's internal choice for implicit casts.

• reinterpret_cast: Applicable when:

  • Converting integer types to pointer types (and vice versa)
  • Casting between pointer types (generally unsafe and discouraged)

void* and Class Interconversion

In your scenario, where C is called from C and a C object must be stored in a C void*, the appropriate cast is:

C++Class* myClass = static_cast<C++Class*>(voidPointer);

Why static_cast?

According to the C standard, static_casting a pointer to and from void* maintains the address. This ensures that after casting and converting back, the original address is preserved.

Additional Note

reinterpret_cast provides a less secure guarantee. If you reinterpret_cast to a different pointer type and then back, the original value is guaranteed. However, the intermediate void* pointer's value is not specified, making reinterpret_cast less suitable for this use case.

Therefore, for casting to and from void*, static_cast is the preferred choice.

The above is the detailed content of C Casting: When Should I Use `reinterpret_cast` vs. `static_cast` for void* Conversions?. For more information, please follow other related articles on the PHP Chinese website!