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**Edwin Knoppert** · 1 Nov 2004, 06:09 AM

Dynamic strings use Byval StrPtr( a$ )
Fixed strings and asciiz use Byval VarPtr( az )

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**Eric Pearson** · 1 Nov 2004, 06:16 AM

Johan --

Are you asking...

1) How to create an ASCIIZ variable

2) How to write a DECLARE statement for a function (in a DLL) which has an ASCIIZ parameter

3) How to call a function which has already been DECLAREd?

You will need to do all three things. Which one(s) are you not clear about?

-- Eric

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**Michael Mattias** · 1 Nov 2004, 06:40 AM

>I need to pass a pointer to a null terminated string to a dll.

Code:

 DECLARE FUNCTION FOO LIB "MYDLL.DLL"  (sz AS ASCIIZ) AS LONG


FUNCTION Caller() AS LONG
 LOCAL  szSomething AS ASCIIZ * %Required_size

  szSomething  ="Something"
  CALL          Foo (szSomething)

END FUNCTION

FWIW: anytime you have either a DECLARE or a PROCEDURE header with a parameter of " X AS ASCIIZ [* length]" the compiler will generate code at point of call to pass the address of the string data, or error out the compile if you use the wrong data type (Error 480).

[This message has been edited by Michael Mattias (edited November 01, 2004).]

**Johan Klassen** · 1 Nov 2004, 11:52 AM

thanks guys, but still have problems, here's what i have.

Code:

      TYPE MPF              ' multiprecision floating point
         mp_prec AS LONG
         mp_size AS LONG
         mp_expt AS LONG
         mp_limb AS LONG
      END TYPE


      DECLARE SUB cMPFinit CDECL LIB "libgmp-3.dll" ALIAS "__gmpf_init" (X AS MPF,prec AS LONG)
      DECLARE SUB cMPFclear CDECL LIB "libgmp-3.dll" ALIAS "__gmpf_clear" (X AS MPF)
      DECLARE SUB cMPFsprintf CDECL LIB "libgmp-3.dll" ALIAS "__gmp_sprintf" (sz AS ASCIIZ) AS LONG,(fmt AS ASCIIZ) AS LONG,X AS MPF)
      DECLARE SUB cMPFset_str CDECL LIB "libgmp-3.dll" ALIAS "__gmpf_set_str" (X AS MPF,(sz AS ASCIIZ) AS LONG, b AS LONG)
      DECLARE SUB cMPFsqrt CDECL LIB "libgmp-3.dll" ALIAS "__gmpf_sqrt" (Y AS MPF,X AS MPF)


FUNCTION PBMAIN () AS LONG
    DIM x AS MPF
    DIM y AS MPF
    DIM a AS ASCIIZ*63999
    DIM f AS ASCIIZ*256
    a="2"
    f="%17.10Fe"
    CALL cMPFinit(x,512)
    CALL cMPFinit(y,512)
    CALL cMPFset_str(x,a,10)
    a=SPACE$(100)
    CALL cMPFsqrt(y,x)
    CALL cMPFsprintf(f,a,y)
    CALL cMPFclear(x)
    CALL cMPFclear(y)
    MSGBOX a

END FUNCTION

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[This message has been edited by Johan Klassen (edited November 01, 2004).]

**Michael Mattias** · 1 Nov 2004, 12:50 PM

Those DECLAREs won't (shouldn't, anyway) compile. You have extra parens around individual parameters.

And this this one...

Code:

DECLARE SUB cMPFset_str CDECL LIB "libgmp-3.dll" ALIAS "__gmpf_set_str" (X AS MPF,(sz AS ASCIIZ) AS LONG, b AS LONG)

..has a parameter of

"(sz AS ASCIIZ) AS LONG"

.. which is totally from somewhere I've never been. Which is it, ASCIIZ or LONG? Can't be both.

Since you've obviously put forth some effort, I don't think anyone will mind if you post the "C" declarations and ask for a little help converting.

[This message has been edited by Michael Mattias (edited November 01, 2004).]

**Johan Klassen** · 1 Nov 2004, 05:32 PM

this was my first try.

Code:

#COMPILE EXE
      TYPE MPF              ' multiprecision floating point
         mp_prec AS LONG
         mp_size AS LONG
         mp_expt AS LONG
         mp_limb AS LONG
      END TYPE

      DECLARE SUB cMPFinit CDECL LIB "libgmp-3.dll" ALIAS "__gmpf_init" (X AS MPF,prec AS LONG)
      DECLARE SUB cMPFclear CDECL LIB "libgmp-3.dll" ALIAS "__gmpf_clear" (X AS MPF)
      DECLARE SUB cMPFsprintf CDECL LIB "libgmp-3.dll" ALIAS "__gmp_sprintf" (s AS STRING,fmt AS STRING,X AS MPF)
      DECLARE SUB cMPFset_str CDECL LIB "libgmp-3.dll" ALIAS "__gmpf_set_str" (X AS MPF,s AS STRING, b AS LONG)
      DECLARE SUB cMPFsqrt CDECL LIB "libgmp-3.dll" ALIAS "__gmpf_sqrt" (Y AS MPF,X AS MPF)


FUNCTION PBMAIN () AS LONG
    DIM x AS MPF
    DIM y AS MPF
    DIM a AS STRING
    DIM f AS STRING
    a="2"
    f="%17.10Fe"
    CALL cMPFinit(x,512)
    CALL cMPFinit(y,512)
    CALL cMPFset_str(x,a,10)
    a=SPACE$(20)
    CALL cMPFsqrt(y,x)
    CALL cMPFsprintf(a,f,y)
    CALL cMPFclear(x)
    CALL cMPFclear(y)
    MSGBOX a

END FUNCTION

but the message box gives "%17.10Fe" when it should be " 1.4142135624e+00"

my second try

Code:

#COMPILE EXE
      TYPE MPF              ' multiprecision floating point
         mp_prec AS LONG
         mp_size AS LONG
         mp_expt AS LONG
         mp_limb AS LONG
      END TYPE

      DECLARE SUB cMPFinit CDECL LIB "libgmp-3.dll" ALIAS "__gmpf_init" (X AS MPF,prec AS LONG)
      DECLARE SUB cMPFclear CDECL LIB "libgmp-3.dll" ALIAS "__gmpf_clear" (X AS MPF)
      DECLARE SUB cMPFsprintf CDECL LIB "libgmp-3.dll" ALIAS "__gmp_sprintf" (s AS STRING POINTER,fmt AS STRING POINTER,X AS MPF)
      DECLARE SUB cMPFset_str CDECL LIB "libgmp-3.dll" ALIAS "__gmpf_set_str" (X AS MPF,s AS STRING POINTER, b AS LONG)
      DECLARE SUB cMPFsqrt CDECL LIB "libgmp-3.dll" ALIAS "__gmpf_sqrt" (Y AS MPF,X AS MPF)


FUNCTION PBMAIN () AS LONG
    DIM x AS MPF
    DIM y AS MPF
    DIM a AS STRING POINTER
    DIM f AS STRING POINTER
    @a="2"
    @f="%17.10Fe"
    CALL cMPFinit(x,512)
    CALL cMPFinit(y,512)
    CALL cMPFset_str(x,a,10)
    @a=SPACE$(20)
    CALL cMPFsqrt(y,x)
    CALL cMPFsprintf(a,f,y)
    CALL cMPFclear(x)
    CALL cMPFclear(y)
    MSGBOX @a

END FUNCTION

program crashes
------------------

trhird try

Code:

#COMPILE EXE
      TYPE MPF              ' multiprecision floating point
         mp_prec AS LONG
         mp_size AS LONG
         mp_expt AS LONG
         mp_limb AS LONG
      END TYPE


      DECLARE SUB cMPFinit CDECL LIB "libgmp-3.dll" ALIAS "__gmpf_init" (X AS MPF,prec AS LONG)
      DECLARE SUB cMPFclear CDECL LIB "libgmp-3.dll" ALIAS "__gmpf_clear" (X AS MPF)
      DECLARE SUB cMPFsprintf CDECL LIB "libgmp-3.dll" ALIAS "__gmp_sprintf" (s AS ASCIIZ PTR,fmt AS ASCIIZ PTR,X AS MPF)
      DECLARE SUB cMPFset_str CDECL LIB "libgmp-3.dll" ALIAS "__gmpf_set_str" ( X AS MPF,s AS ASCIIZ PTR,b AS LONG)
      DECLARE SUB cMPFsqrt CDECL LIB "libgmp-3.dll" ALIAS "__gmpf_sqrt" (Y AS MPF,X AS MPF)


FUNCTION PBMAIN () AS LONG
    DIM x AS MPF
    DIM y AS MPF
    DIM a AS ASCIIZ*2000
    DIM f AS ASCIIZ*20
    a="2"
    f="%17.10Fe"
    CALL cMPFinit(x,512)
    CALL cMPFinit(y,512)
    CALL cMPFset_str(x,VARPTR(a),10)
    a=SPACE$(20)
    CALL cMPFsqrt(y,x)
    CALL cMPFsprintf(VARPTR(a),VARPTR(f),y)
    CALL cMPFclear(x)
    CALL cMPFclear(y)
    MSGBOX a

END FUNCTION

*crash*
maybe i should give up.

if i understand the powerbasic documentation corectly:

Code:

DIM s AS ASCIIZ*20
DIM p AS LONG
s="hello"
p=VARPTR(s)

p points to the memory location that contains the string "hello"
what i need is a pointer to a pointer to string, how do declare such a beast?

[This message has been edited by Johan Klassen (edited November 01, 2004).]

**Tom Hanlin** · 2 Nov 2004, 11:00 AM

It looks like you're making this more complicated than it needs to be
but:

pp = VARPTR(p)

You can pass this as "BYVAL pp" in your call, as needed.

------------------
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Opinions expressed may not be those of my employer or myself

**Johan Klassen** · 2 Nov 2004, 11:32 AM

thanks for all your replies, and i appologize for my lack of
communication skills.

for what it's worth, here's the working version.

Code:

'you can download gmp from [url="http://www.cs.nyu.edu/exact/core/gmp/"]http://www.cs.nyu.edu/exact/core/gmp/[/url] 

#COMPILE EXE

      TYPE MPF              ' multiprecision floating point
         mp_prec AS LONG
         mp_size AS LONG
         mp_expt AS LONG
         mp_limb AS LONG
      END TYPE


      DECLARE SUB cMPFinit CDECL LIB "libgmp-3.dll" ALIAS "__gmpf_init2" (BYREF X AS MPF,BYVAL prec AS LONG)
      DECLARE SUB cMPFclear CDECL LIB "libgmp-3.dll" ALIAS "__gmpf_clear" (BYREF X AS MPF)
      DECLARE SUB cMPFsprintf CDECL LIB "libgmp-3.dll" ALIAS "__gmp_sprintf" (BYREF s AS ASCIIZ,BYREF fmt AS ASCIIZ,BYREF X AS MPF)
      DECLARE SUB cMPFset_str CDECL LIB "libgmp-3.dll" ALIAS "__gmpf_set_str" (BYREF X AS MPF,BYREF s AS ASCIIZ,BYVAL b AS LONG)
      DECLARE SUB cMPFsqrt CDECL LIB "libgmp-3.dll" ALIAS "__gmpf_sqrt" (BYREF Y AS MPF,BYREF X AS MPF)


FUNCTION PBMAIN () AS LONG
    DIM x AS MPF
    DIM y AS MPF
    DIM a AS ASCIIZ*2000
    DIM f AS ASCIIZ*20
    a="2"
    f="%77.70Fe"
    CALL cMPFinit(x,512)'initialize x to 512 bit precision
    CALL cMPFinit(y,512)
    CALL cMPFset_str(x,a,10)'set x to value of a base 10
    a=SPACE$(100)'reserve space for sprintf
    CALL cMPFsqrt(y,x)'y=sqrt(x)
    CALL cMPFsprintf(a,f,y)'sprintf the value of y into the string a
    CALL cMPFclear(x)'deallocate
    CALL cMPFclear(y)
    MSGBOX a

END FUNCTION

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[This message has been edited by Johan Klassen (edited November 02, 2004).]

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how to pass a pointer to a null terminated string?

how to pass a pointer to a null terminated string?

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