RosettaCodeData/Task/Roman-numerals-Decode/XBasic/roman-numerals-decode.basic

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PROGRAM "romandec"
VERSION "0.0000"
DECLARE FUNCTION Entry ()
DECLARE FUNCTION romToDec (roman$)
FUNCTION Entry ()
PRINT "MCMXCIX = "; romToDec("MCMXCIX")
PRINT "MDCLXVI = "; romToDec("MDCLXVI")
PRINT "XXV = "; romToDec("XXV")
PRINT "CMLIV = "; romToDec("CMLIV")
PRINT "MMXI = "; romToDec("MMXI")
END FUNCTION
FUNCTION romToDec (roman$)
num = 0
prenum = 0
FOR i = LEN(roman$) TO 1 STEP -1
x$ = MID$(roman$, i, 1)
SELECT CASE x$
CASE "M" : n = 1000
CASE "D" : n = 500
CASE "C" : n = 100
CASE "L" : n = 50
CASE "X" : n = 10
CASE "V" : n = 5
CASE "I" : n = 1
END SELECT
IF n < prenum THEN num = num-n ELSE num = num+n
prenum = n
NEXT i
RETURN num
END FUNCTION
END PROGRAM