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`rindex'--reverse search for character in string

     #include <string.h>
     char * rindex(const char *STRING, int C);
This function finds the last occurence of C (converted to a char) in
the string pointed to by STRING (including the terminating null
   This function is identical to `strrchr'.
Returns a pointer to the located character, or a null pointer if C does
not occur in STRING.
`rindex' requires no supporting OS subroutines.