call c dll from delphi with strings -

i trying call dll delphi xe5.

i have spent day or googling things "call c dll delphi" , found number of pages nothing helped me.

i have received examples of how call dll in vb:

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declare function ixcommand lib "ixxdll.dll" (byval command string, byval mailbox string) integer  ...  sub command1_click ()          dim command string * 135          dim mailbox string * 135           command = "move:a,1000"          ixcommand( command, mailbox) end sub 

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also calling dll in vc 6.0:

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#include "stdafx.h"  #include "windows.h" #include "stdio.h" #include "string.h"  typedef uint (callback* lpfnixdllfunc)(char *ixstr, char *mbstr);  int main(int argc, char* argv[]) {     hinstance hdll;              // handle dll     lpfnixdllfunc lpfnixdllfunc; // function pointer      hdll = loadlibrary( "ixxdll.dll" );      if (hdll == null) // fails load indexer lpt     {         printf("can't open ixxdll.dll\n");         exit(1);     }     else // success opening dll - dll function pointer     {         lpfnixdllfunc = (lpfnixdllfunc)getprocaddress(hdll, "ixcommand");     }      printf( "type indexer lpt command , press <enter> send\n" );     printf( "type \"exit\" , press <enter> quit\n\n" );      while( 1 )     {         char ix_str[135];      // string sent indexer lpt         char mailbox_str[135]; // results call indexer lpt          gets( ix_str ); // string console         if( _stricmp( ix_str, "exit" ) == 0 ) // leave program if "exit"             break;         lpfnixdllfunc( ix_str, mailbox_str ); // otherwise call indexer lpt         printf( "%s\n\n", mailbox_str );      // print results     }      freelibrary( hdll );     return 0; } 

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a complication have noticed need define size of memory allocation before calling dll, shown above.

the dll takes command in first argument , returns result text in second argument.

here delphi code have generated try , call dll. know dll loads because has splash screen shows. no error generated when call dll. see used arrays allocate space , assigned locations pchar variables. not have header file original dll, nor source code. see declared external function using stdcall have tried cdecl no change.

the problem: information returned in arg2 not expected text string string of translates non-english characters (looks chinese).

i guessing not sending dll correct variable types.

the question: can me formulate declaration of external function , use correctly, text strings desired?

see below:

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function ixcommand (command : pchar; mailbox : pchar) : integer; stdcall; external 'ixxdll.dll';  ...  procedure tfrmxyz.btn1click(sender: tobject);  var   localresult : integer;   arg1,   arg2        : pchar;     arraystrcmd : array[0..134] of char;   arraystrmbx : array[0..134] of char;  begin    arraystrcmd := 'accel?:a' + #0;   arraystrmbx := '          ' + #0;   arg1 := @arraystrcmd;   arg2 := @arraystrmbx;     localresult := ixcommand(arg1, arg2);  end; 

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the problem character encodings. in delphi 2009+, pchar alias pwidechar, dll using ansi character strings instead, need use pansichar instead of pchar.

try this:

function ixcommand (command : pansichar; mailbox : pansichar) : integer; stdcall; external 'ixxdll.dll';  ...  procedure tfrmxyz.btn1click(sender: tobject); var   localresult : integer;   arraystrcmd : array[0..134] of ansichar;   arraystrmbx : array[0..134] of ansichar; begin   arraystrcmd := 'accel?:a' + #0;   localresult := ixcommand(arraystrcmd, arraystrmbx); end; 

alternatively:

function ixcommand (command : pansichar; mailbox : pansichar) : integer; stdcall; external 'ixxdll.dll';  ...  procedure tfrmxyz.btn1click(sender: tobject); var   localresult : integer;   arraystrcmd,   arraystrmbx : ansistring; begin   setlength(arraystrcmd, 135);   strpcopy(arraystrcmd, 'accel?:a');   setlength(arraystrmbx, 135);   localresult := ixcommand(pansichar(arg1), pansichar(arg2)); end;