illegal function call

[Mel Bishop]

in another post, http://www.powerbasic.com/support/pb...ad.php?t=20285
i asked for a more efficient way to sort the letters in a word.
jose's reply sparked a remembrence and i modified a short sort
routine i developed in the days of the ti/99-4a.

got it to work okay in cc but since cc doesn't have mtimer, i
copied it over the pb/dos and did some minor restructure so i
could see how fast it operates. here is the dos version:

    $lib all off
    $error all on
    color 14,1
    cls

    text$ = "zyxwvutsrqponmlkjihgfedcba"
    locate 1,1 : print;text$;

    text$ = sortword$(text$)
    locate 2,1 : print;text$;
    end

function sortword$(text$)

    for x = 2 to len(text$)
    l = x

10  do until mid$(text$,l,1) => mid$(text$,l-1,1) or l = 1

    s1$ = mid$(text$,l-1,1)
    mid$(text$,l-1,1) = mid$(text$,l,1)
    mid$(text$,l,1) = s1$
    l = l - 1

    loop
    next x
    function = text$

    end function

it compiles okay but trying to run it produces an "illegal function
call" on line 10 and i can't figure out why. the exact same thing
compiles and runs fine under cc but not dos. i am running xp/pro.

any ideas? thanks.


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[this message has been edited by mel bishop (edited october 19, 2003).]

[Michael Mattias]

DO UNTIL MID$(text$,L,1) => MID$(text$,L-1,1) OR L = 1

Not tested, but....

You need to check if L=1 BEFORE you use 'L-1' in the MID$ statement, otherwise you are taking MID$(text$, 0,....)

So try this..

DO UNTIL L=1 OR MID$(text$,L,1) => MID$(text$,L-1,1)

.. to force exit before the illegal MID$ statement is even attempted.


MCM

[Don Schullian]

Mel,

Here's a function and a 2 liner you can use. IIRC PB/DOS did things like this.
DIM A(1 TO LEN(Text)) AS BYTE AS STRPTR(Text)
ARRAY SORT A()

FUNCTION SortWord ( BYVAL Text AS STRING ) AS STRING

  DIM L AS LOCAL INTEGER
  L = LEN(Text)

  IF L > 1 THEN
    DIM A(L-1) AS BYTE AT STRPTR(Text)
    ARRAY SORT A()
  END IF
  
  FUNCTION = Text

END FUNCTION

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C'ya
Don
[email protected]