/sys$common/syshlp/helplib.hlb CC, Run-time functions, memchr  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  Locates the first occurrence of the specified byte within the
  initial size bytes of a given object.

  Syntax:

       #include <string.h>

       void *memchr (const void *s1, int c, size_t size);