The C compiler can accept a pointer that you typecast to another pointer type as an lvalue.

For example:

char *cp;
((long *) cp)++;  /* OK if ANSI Strict is off. */

To turn this feature on, turn off the ANSI Strict setting in the C/C++ Language Panel. If the ANSI Strict setting is on, then this extension to standard C is disabled.

See also: "ANSI Strict."