LoadLibrary and string issue

Hi to all
I am making a software with Visual Studio 2008, writing in C++ (no MFC).

I would like to load some DLL dynamically.

Following msdn example (ms-help://MS.MSDNQTR.v90.it/dllproc/base/using_run_time_dynamic_linking.htm), I would like to create a funcion address like this:

funct_addr = (MYPROC) GetProcAddress(hinstDLL, "myDLLFunct");

and subsequently calling this function like this:
(funct_addr) (L"Message sent to the DLL function\n");

My question is: how could I call a funcion which argouments are made by strings?
In my code, I have the following function:
myDLLFunct("string1","string2");
How could I call it? I can't do something like this:
(funct_addr) (L""string1","string2"");

Thank's for your help!

I'm not sure if I got your question right, but from what I understand (and if one removes obvious typos, or errors/VB left-overs, like L""string1","string2""), every API function that has a string in one of its arguments, imported dynamically through the call to GetProcAddress() must be specifically identified by its ANSI/Unicode name. Here's an example:

Code:

---

HANDLE hMod = LoadLibrary(_T("User32.dll"));
#ifdef _UNICODE
(FARPROC&)fnPtr = GetProcessAddress(hMod, _T("OpenDesktopW"));
#else
(FARPROC&)fnPtr = GetProcessAddress(hMod, _T("OpenDesktopA"));
#end

if(fnPtr)
    fnPtr(_T("Screen-saver"), 0, FALSE, NULL);

---

You'd also better use _T("") macro on all of your strings to facilitate ANSI/Unicode conversion.

Quote:

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Originally Posted by motobizio

In my code, I have the following function:
myDLLFunct("string1","string2");
How could I call it? I can't do something like this:
(funct_addr) (L""string1","string2"");

---

You call the function using the parameters that it requires.

If this is the prototype of the function:

void myDLLFunct(const char *, const char *);

Then you call it using a pointer obtained from GetProcAddress() like this:

funct_addr("string 1", "string 2");

And as dc_2000 noted, be careful when using _T() MACROS. Once a dll has been compiled you must know what type of strings it requires so _T() may not be appropriate. Microsoft usually provides two versions 'A' and 'W' as indicated above.

You can always #ifdef _UNICODE your function prototypes (providing both A and W versions are available) so that you can be consistent with the Win32 api's and continue to use LPTSTR and _T("").

First of all Thank you for your help.

For dc_2000:
I tried to do something like this:
funct_addr(_T"("string1","string2")");
but it returns following error:
error C2197: too many argouments for a calling

For 0xC0000005:
I tried to do something like this:
funct_addr(L""string1","string2"");
but it returns following error:
error C2146: syntacs error: ')' missing before string1 argoument

For Arjay:
My project is in UNICODE: I put UNICODE directive in project property

Let me explain well.

I have 2 functions from the same DLL:
myDLLFunct1(int arg1, int arg2);
myDLLFunct2(TCHAR* pstring1, TCHAR* pstring2)

I would like to assign an address for those 2 functions by this way:
funct1_addr = (MYPROC) GetProcAddress(hinstDLL, "myDLLFunct1");
funct2_addr = (MYPROC) GetProcAddress(hinstDLL, "myDLLFunct2");

and subsequently calling this function like this:
funct1_addr (L"arg1, arg2");
funct2_addr (L""string1","string2"");

Well, funct1_addr works OK, while funct2_addr doesn't work because of errors during compile action.

Does anyone know how could I pass those strings as argouments?

Thank you again!

Quote:

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Originally Posted by motobizio

and subsequently calling this function like this:
funct1_addr (L"arg1, arg2");
funct2_addr (L""string1","string2"");

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Why are you enclosing the parameters in quotes? That is not needed! The function calls should look as follows:

Code:

---


funct1_addr (arg1, arg2);
funct2_addr ("string1","string2");

---

Quote:

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Originally Posted by kolkoo

Why are you enclosing the parameters in quotes? That is not needed! The function calls should look as follows:

Code:

---


funct1_addr (arg1, arg2);
funct2_addr ("string1","string2");

---

---

Because if I write as you suggest:
funct1_addr(arg1, arg2);
the compiler returns following error:
error C2197: too many argouments for a calling

I defined my funct_addr type like this (I found it in a mdsn example):

Code:

---


typedef int (__cdecl *MYPROC)(LPWSTR);
MYPROC funct1_addr ;

---

then you should call it this way:

Code:

---

funct1_addr("String parameter here!");

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Well I partially solved it.
The problem was in the function type of funct_addr.
I declared it like mdsn example by this way:
typedef int (__cdecl *MYPROC)(LPWSTR);
MYPROC funct1_addr ;

Now, declaring as (FARPROC&) (Thank's a lot dc_2000) the compilation results OK!!!

Thanks to all of you!!

But now I have another issue.
Actually I link my dll in implicit way, by passing MyDll.lib in the linker section of project property sheet.
Because of I would like to charge it dinamically, I avoid the link to DLL in the linker section, and insert it in my code with Loadlibrary() function. This fact cause a no good compilation because linker can't find funct1_addr.

Where I fault this time?