SCAN SAVE-INPUT SCR
SCAN
* SCAN ( str len char -- str+i len-i )

Look for a particular character in the specified string. 
 : SCAN     
    >R  BEGIN  DUP WHILE  OVER C@ R@ -
        WHILE  1 /STRING  REPEAT THEN
    R> DROP ;

ie.
scan for first occurence of c in string 
   : SCAN >R BEGIN DUP OVER C@ R@ = 0= OR WHILE 
                    1- SWAP 1- SWAP REPEAT R> DROP ;

toolbelt ordinary primitive