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

  Returns the length of a string of ASCII characters.  The returned
  length does not include the terminating null character (\0).

  Syntax:

       #include <string.h>

       size_t strlen(const char *str);