Faster addition in string math. Now with multiplication!

[Pete]

Actually, I already had all of that needed stuff in my old routine, but I'm attempting to shave a few lines off by using a sightly different method here, plus adding in the 18 digits at a time method for speed improvement.

Code: (Select All)

DIM AS _INTEGER64 a
WIDTH 130, 42
_SCREENMOVE 0, 0

DO
    LINE INPUT "Number: "; a$
    IF a$ = "" THEN EXIT DO ' Quit.
    LINE INPUT "+ or -: "; op$
    LINE INPUT "Number: "; b$

    a1$ = a$: b1$ = b$

    IF op$ = "-" THEN
        IF LEFT$(b$, 1) = "-" THEN b$ = MID$(b$, 2) ELSE b$ = "-" + b$
    END IF

    s = 18
    IF INSTR(a$, ".") <> 0 OR INSTR(b$, ".") <> 0 THEN
        decimal% = -1
        IF INSTR(a$, ".") <> 0 THEN
            dec_a&& = LEN(MID$(a$, INSTR(a$, ".") + 1))
            a$ = MID$(a$, 1, INSTR(a$, ".") - 1) + MID$(a$, INSTR(a$, ".") + 1)
        END IF
        IF INSTR(b$, ".") <> 0 THEN
            dec_b&& = LEN(MID$(b$, INSTR(b$, ".") + 1))
            b$ = MID$(b$, 1, INSTR(b$, ".") - 1) + MID$(b$, INSTR(b$, ".") + 1)
        END IF
        ' Line up decimal places by inserting trailing zeros.
        IF dec_b&& > dec_a&& THEN
            j&& = dec_b&&
            a$ = a$ + STRING$(dec_b&& - dec_a&&, "0")
        ELSE
            j&& = dec_a&&
            b$ = b$ + STRING$(dec_a&& - dec_b&&, "0")
        END IF
    END IF

    IF LEFT$(a$, 1) = "-" OR LEFT$(b$, 1) = "-" THEN
        IF LEFT$(a$, 1) = "-" AND LEFT$(b$, 1) = "-" THEN
            sign$ = "--": a$ = MID$(a$, 2): b$ = MID$(b$, 2)
        ELSE
            IF LEFT$(a$, 1) = "-" THEN a$ = MID$(a$, 2): sign_a$ = "-"
            IF LEFT$(b$, 1) = "-" THEN b$ = MID$(b$, 2): sign_b$ = "-"
            IF ABS(VAL(a1$)) < ABS(VAL(b1$)) THEN
                IF LEN(sign_b$) THEN sign$ = "-": SWAP a$, b$
            ELSE
                IF LEN(sign_a$) THEN sign$ = "-": SWAP sign_a$, sign_b$
            END IF
        END IF
    END IF

    z$ = ""
    DO
        i&& = i&& + s
        x1$ = MID$(a$, LEN(a$) - i&& + 1, s)
        x2$ = MID$(b$, LEN(b$) - i&& + 1, s)
        a = VAL(sign_a$ + x1$) + VAL(sign_b$ + x2$) + c
        IF x1$ + x2$ = "" AND c = 0 THEN EXIT DO ' Prevents leading zeros.
        c = 0
        IF a > VAL(STRING$(s, "9")) THEN a = a - 10 ^ (s): c = 1
        IF a < 0 THEN a = a + 10 ^ (s): c = -1
        z$ = LTRIM$(STR$(a)) + z$
        REM PRINT x1$;: LOCATE , 15: PRINT x2$;: LOCATE , 30: PRINT VAL(x1$) - VAL(x2$);: LOCATE , 45: PRINT c;: LOCATE , 60: PRINT a, z$: SLEEP
    LOOP

    IF decimal% THEN
        z$ = MID$(z$, 1, LEN(z$) - j&&) + "." + MID$(z$, LEN(z$) - j&& + 1)
    END IF

    ' Remove any leading zeros.
    DO
        IF LEFT$(z$, 1) = "0" THEN z$ = MID$(z$, 2) ELSE EXIT DO
    LOOP
    IF z$ = "" THEN z$ = "0"

    z$ = LEFT$(sign$, 1) + z$

    IF op$ = "+" THEN PRINT " " + LTRIM$(STR$(VAL(a1$) + VAL(b1$))), "QB64 VAL()." ELSE PRINT " " + LTRIM$(STR$(VAL(a1$) - VAL(b1$))), "QB64 VAL()."
    PRINT " "; z$, "String Math."
    PRINT
    sign$ = "": sign_a$ = "": sign_b$ = "": i&& = 0: j&& = 0: decimal% = 0: c = 0
LOOP
SYSTEM

Fingers crossed, few to no bugs.

Thanks for the inspiration,

Pete