PROGRAM  "Rot-13"
VERSION  "0.0000"

DECLARE FUNCTION  Entry ()

FUNCTION  Entry ()
	dec$ = ""
	TYPE$ = "cleartext "
	ctext$ = ""
	iOffset = 13    'offset assumed to be 13 - uncomment line 11 to change

	PRINT "For decrypt enter " + "<d> " + " -- else press enter > ";
	dec$ = INLINE$("")
	PRINT

	IF LCASE$(dec$) = "d" THEN
		iOffset = 26 - iOffset
		TYPE$ = "ciphertext "
	END IF

	PRINT "Enter " + TYPE$; '' + "> ";
	cad$ = UCASE$(INLINE$("> "))

	FOR i = 1 TO LEN(cad$)
		iTemp =  ASC(MID$(cad$,i,1))
		IF iTemp > 64 AND iTemp < 91 THEN
			iTemp = ((iTemp - 65) + iOffset) MOD 26
			PRINT CHR$(iTemp + 65);
		END IF
	NEXT i
END FUNCTION
END PROGRAM