Thread: Creating DLL in MS VS 6.0 in C

Using Visual Studio 6 C++ (but programming C)

1. Have created new project of type Win32 Dynamic Link Library.

2. Have got all c code (i.e. imported from standard project I made earlier), headers and external dependancies set up and imported.

3. Have turned of precompiled headers.

4. In main () I have included:

Code:

#include <windows.h>
#include <dos.h>

5. I have been following instuctions as outlined in this web link
http://support.microsoft.com/default...b;en-us;106553

I cant go any further in this link when I try to compile because I get these strange compile errors.

Code:

c:\program files\microsoft visual studio\vc98\include\windef.h(43) : warning C4114: same type qualifier used more than once
c:\program files\microsoft visual studio\vc98\include\windef.h(43) : error C2632: 'long' followed by 'long' is illegal
c:\program files\microsoft visual studio\vc98\include\windef.h(43) : warning C4091: 'typedef ' : ignored on left of 'unsigned long ' when no variable is declared
c:\program files\microsoft visual studio\vc98\include\windef.h(45) : warning C4114: same type qualifier used more than once
c:\program files\microsoft visual studio\vc98\include\windef.h(45) : error C2632: 'short' followed by 'short' is illegal
c:\program files\microsoft visual studio\vc98\include\windef.h(45) : warning C4091: 'typedef ' : ignored on left of 'unsigned short ' when no variable is declared...........

and so on..

Does anyone have any any clear and comprehensive instuctions, web links etc on how you accomplish making dll's in this envionment - as I think the link I am following is out of date (and a little confusing, as I have never created a dll before).

Many thanks
Simon

It looks like you are trying to compile C code as C++.

Originally Posted by earnshaw

Using Visual Studio 6 C++ (but programming C)


I cant go any further in this link when I try to compile because I get these strange compile errors.

Code:

c:\program files\microsoft visual studio\vc98\include\windef.h(43) : warning C4114: same type qualifier used more than once
c:\program files\microsoft visual studio\vc98\include\windef.h(43) : error C2632: 'long' followed by 'long' is illegal

and so on..

Does anyone have any any clear and comprehensive instuctions, web links etc on how you accomplish making dll's in this envionment - as I think the link I am following is out of date (and a little confusing, as I have never created a dll before).

Many thanks
Simon

Visual Studio 6 doesn't have long long data types (at least mine doesn't).
You might want to get Visual C++ 2005 Express. (Free download).

If you want to use VS6, the data type is __int64:

Code:

/* use of 64-bit ints with Microsoft Visual Studio 6 */
#include <stdio.h>                                    
typedef unsigned __int64 Long; /* typedef for my convenience */
int main()                                       
{                                                     
   Long juul = 123456789012345678L;    

   printf("sizeof(Long) = %d\n", sizeof (Long));
   printf("juul: %I64d (decimal)\n",juul);
   printf("juul: 0x%016I64X (hex)\n",juul);                     
   return 0;
}

Regards,

Dave

That isn't C code. C doesn't have new or delete, and I believe it doesn't have references. Try this:

Code:

In c_dll_4_vb.c
long __stdcall Resolve_Name_To_Ip
  (char *pcDomainToResolve, char szReturnIP[500], int* iSize)
{
	  WSADATA		wsaData;					
	  //LPTSTR		CompName = new char[255];
	  LPTSTR		CompName = malloc(sizeof(char)*255);
	  //LPDWORD		CompSize = new unsigned long(255);
	  LPDWORD		CompSize = malloc(sizeof(unsigned long)*255);

	  struct		sockaddr_in dest;
	  struct		hostent *hp;
	  char			*dest_ip;

	  unsigned int	addr = 0;

	  strcpy(CompName,pcDomainToResolve);

	  if(WSAStartup(MAKEWORD(2,1), &wsaData) != 0)
	  {  WSACleanup();
		 return -100;
	  }

	  hp = gethostbyname(CompName);
	  if(!hp)
	  {  addr = inet_addr(CompName);	
	  }

	  if((!hp) && (addr == INADDR_NONE))
	  {// Unable to resolve domain ip.
		WSACleanup();
		return -200;
	  }

	  hp = gethostbyname(CompName);
	  if(hp != NULL)
		memcpy(&(dest.sin_addr),hp->h_addr,hp->h_length);
	  else
		dest.sin_addr.s_addr = addr;

	  if(hp)
		dest.sin_family = hp->h_addrtype;
	  else
		dest.sin_family = AF_INET;

	  dest_ip = inet_ntoa(dest.sin_addr);
		
	  *iSize = strlen(dest_ip);
		
	  // Allow the string to return to the proper size.
	  strncpy(szReturnIP, dest_ip, strlen(dest_ip)); 
		
	  dest_ip = NULL;
	  hp = NULL;
	  addr = 0;
	  //dest.sin_family = NULL;
	  //dest.sin_addr.s_addr = NULL;	
	  //dest.sin_addr.S_un.S_addr = NULL;
	  //dest.sin_port = NULL;
	  dest.sin_family = 0;
	  dest.sin_addr.s_addr = 0;	
	  dest.sin_addr.S_un.S_addr = 0;
	  dest.sin_port = 0;

	  free(CompName);
	  free(CompSize);

	  WSACleanup();
	  return (0);
}

In c_dll_4_vb.h
#include <windows.h>
#include <winsock.h>
#include <stdio.h>

// Function is used to resolve a domain name to an IP address.
// The return values are: -100 = Incorrect version of Winsock
//                        -200 = Cant resolve domain.
long __stdcall Resolve_Name_To_Ip
    (char *pcDomainToResolve, char szReturnIP[500], int *iSize);