[Solved] What is the result of casting in C++?

Question

In this context, 0 is a null pointer constant. It can be converted, with or without a cast, to any pointer type, giving a null pointer of that type. In modern C++, you can write nullptr to make it more clear that you mean a null pointer, not the number zero. There’s also a NULL macro for the same purpose.

So here you have two pointers: one points to the string literal’s array of characters, the other is null, and doesn’t point to anything.

Dereferencing a null pointer gives undefined behaviour; typically, a segmentation fault, as you encountered.

Note that, in modern C++, you’ll need const char * in order to point to the constant string literal "hello". Older versions of the language allowed the dangerous conversion to a non-const char * for compatibility with ancient C code that didn’t have a concept of const; that nastiness has now finally been removed from the language.

Accepted Answer

In this context, 0 is a null pointer constant. It can be converted, with or without a cast, to any pointer type, giving a null pointer of that type. In modern C++, you can write nullptr to make it more clear that you mean a null pointer, not the number zero. There’s also a NULL macro for the same purpose.

So here you have two pointers: one points to the string literal’s array of characters, the other is null, and doesn’t point to anything.

Dereferencing a null pointer gives undefined behaviour; typically, a segmentation fault, as you encountered.

Note that, in modern C++, you’ll need const char * in order to point to the constant string literal "hello". Older versions of the language allowed the dangerous conversion to a non-const char * for compatibility with ancient C code that didn’t have a concept of const; that nastiness has now finally been removed from the language.