Calling DLL functions...

[jaberwacky]

Hi, I'm new to using and making DLLs and so far I made an example DLL and I have filled it with three functions. The functions return an int, float, and char respectively. I can DLLCall the int and float functions but not the char! I'm not sure what's going on. String doesn't seem to work for me either. My search through the forum didn't have any examples which used char. I included the DLL code too just in case. Any thing you throw my way will be surely appreciated.

Global $hDll = DllOpen("D:\CodeBlocks\C++ Programs\Line Alg DLL\bin\Debug\Line Alg DLL.dll")

Global $return = DllCall($hDll, "int:cdecl", "Add", "int", 6, "int", 4) ; <-- works
ConsoleWrite("@error: " & @error & " Returns: " & $return[0] & @CRLF)

Global $return1 = DllCall($hDll, "float:cdecl", "AddF", "float", 5.5, "float", 4.5) ; <-- works
ConsoleWrite("@error: " & @error & " Returns: " & $return1[0] & @CRLF)

Global $return2 = DllCall($hDll, "char:cdecl", "sendChar", "char", 'A') ; <-- doesn't work
ConsoleWrite("@error: " & @error & " Returns: " & $return2[0] & @CRLF)

DllClose($hDll)

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#ifndef __MAIN_H__
#define __MAIN_H__

#include <windows.h>

/* To use this exported function of dll, include this header
 * in your project.
 */

#ifdef BUILD_DLL
    #define DLL_EXPORT __declspec(dllexport)
#else
    #define DLL_EXPORT __declspec(dllimport)
#endif

#ifdef __cplusplus
extern "C"
{
#endif

void DLL_EXPORT SomeFunction(const LPCSTR sometext);

#ifdef __cplusplus
}
#endif

#endif // __MAIN_H__

extern "C" __declspec(dllexport)

int Add(int a, int b )
{
    return a + b;
}

extern "C" __declspec(dllexport)

float AddF(float a , float b )
{
    return a + b;
}

extern "C" __declspec(dllexport)

char sendChar(char letter)
{
    return letter;
}

Edited June 9, 2010 by jaberwocky6669

[Richard Robertson]

Try Asc('A') since char is technically a number.

Edited June 9, 2010 by Richard Robertson

[Malkey]

...

...
Global $return2 = DllCall($hDll, "char:cdecl", "sendChar", "char", 'A') ; <-- doesn't work

...

Is "char" a valid data type parameter for DllCall().

I was thinking "str", but I could be wrong.

[ProgAndy]

what is the return of @error? If @error = 2 you should try byte instead of char and use Asc('A')

Edited June 9, 2010 by ProgAndy

[Ascend4nt]

Yeah, 'char' isn't supported by DLLCall unfortunately. The call would need 'byte' or 'ubyte' and then a simple conversion using BinaryToString().

*edit: Oops, a Chr() conversion would be better

Edited June 9, 2010 by Ascend4nt

[ProgAndy]

@Ascend4nt: Using ubyte is not a good idea. byte is already an unsigned type, so ubyte is unnecessary and can be removed at any time. I think, it already is.

Yes, for this purpose, the functions Asc and Chr are the best.

When you have wchar, you should use "WORD" or "ushort" and AscW/ChrW

[Richard Robertson]

I didn't realize char isn't supported. My bad.

[jaberwacky]

Hai guyz, thanks for the replies! Yes! It took me a minute to figure out what yall meant. Thank you.

Global $hDll = DllOpen("D:\CodeBlocks\C++ Programs\Line Alg DLL\bin\Debug\Line Alg DLL.dll")

Global $return = DllCall($hDll, "int:cdecl", "AddInt", "int", 6, "int", 4) ; <-- works

Report($return[0])

Global $return1 = DllCall($hDll, "float:cdecl", "AddFloat", "float", 5.5, "float", 4.5) ; <-- works

Report($return1[0])

Global $return2 = DllCall($hDll, "str:cdecl", "sendString", "str", "hello") ; <-- works

Report($return2[0])

Global $return3 = DllCall($hDll, "byte:cdecl", "sendChar", "byte", Asc('A')) ; <-- works

Report(Chr($return3[0]))

DllClose($hDll)

Func Report($report)
    Return ConsoleWrite("Return: " & $report & @CRLF)
EndFunc ;==>Report

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"main.h"

//*************************************************
#ifndef __MAIN_H__
#define __MAIN_H__

#include <windows.h>

/* To use this exported function of dll, include this header
 * in your project.
 */

#ifdef BUILD_DLL
    #define DLL_EXPORT __declspec(dllexport)
#else
    #define DLL_EXPORT __declspec(dllimport)
#endif


#ifdef __cplusplus
extern "C"
{
#endif

void DLL_EXPORT SomeFunction(const LPCSTR sometext);

#ifdef __cplusplus
}
#endif

#endif // __MAIN_H__
//*************************************************

#include "main.h"
#include <Windows.h>

using namespace std;

extern "C" __declspec(dllexport)

int AddInt(int a, int b)
{
    return a + b;
}

extern "C" __declspec(dllexport)

float AddFloat(float a , float b)
{
    return a + b;
}

extern "C" __declspec(dllexport)

LPSTR sendString(LPSTR uhhhhh_like_Words_and_Stuff)
{
    return uhhhhh_like_Words_and_Stuff;
}

extern "C" __declspec(dllexport)

char sendChar(char uhhhhh_like_Words_and_Stuff)
{
    return uhhhhh_like_Words_and_Stuff;
}

Edited June 10, 2010 by jaberwocky6669