/* Stub implementation of (obsolete) index(). */
-extern char * strchr();
+/*
+
+@deftypefn Supplemental char* index (char *@var{s}, int @var{c})
+
+Returns a pointer to the first occurrence of the character @var{c} in
+the string @var{s}, or @code{NULL} if not found. The use of @code{index} is
+deprecated in new programs in favor of @code{strchr}.
+
+@end deftypefn
+
+*/
+
+extern char * strchr(const char *, int);
char *
-index (s, c)
- char *s;
- int c;
+index (const char *s, int c)
{
return strchr (s, c);
}