Extended MAPI in C, not C++ or C#

[panther82]

I need to modify a few C applications that are about 10 years old and are currently using CMC to send and receive email from Exchange. I tried using Simple MAPI but am encountering the Outlook security prompts, so I am now looking at using Extended MAPI. I have found examples here using C++, but nothing written in C. Microsoft does not seem to offer much in the way of examples and rewriting the applications in C++ is not an option because there are several custom libraries that would also need to be converted. One of the applications is loaded on about 15,000 workstations, so a third party product or a loading a custom dll is not an option either. The only functionality I need is to be able to logon, logoff, send email and read email (in plain text). Any ideas ??

[Member 754960]

This doesn't add up. You don't need to rewrite the whole application in C++. You should be able to interface the legacy C code with any C++ changes. Write a C interface to the C++ code:

// legacy C code

#include "NewCppAPI.h"

void legacy_Code()
{
// doing things with stable code
// call the new code
int iResult = NewCppAPI();
// check return code
}

// NewCppAPI.h

#ifdef __cplusplus
extern "C" {
#endif

int NewCppAPI();

#ifdef __cplusplus
}
#endif

// NewCppAPI.cpp

#include "NewCppAPI.h"

int NewCppAPI()
{
int iResult = 0;

// do the new stuff

return iResult;

}

I have to guess that there must be some other constraints you are not mentioning.

[Member 754960]

further...I would anticipate that you might need to interface to the legacy C code from the C++ code. In the C++ code mark the legacy C headers as C code:

// legacycode.h

extern int stableAPI(int icount);

// NewCppAPI.cpp

extern "C" {
#include "legacycode.h"
}

void CppFunction()
{
// do new things
std::vector <int> vNumbers;
vNumbers.push(1);
vNumbers.push(2);
vNumbers.push(3);

// call the stable code
int iResult = stableAPI(vNumbers.size());

}

When you have to pass information to the legacy code, it can only pass C types; don't pass pointers to C++ types. Be sure you know who owns what memory. A simple solution is to write copy API's in the C++ code that are called by the legacy C code in the same way that windows API's do. You pass in a pointer to a buffer with a pointer to a length that is the size of the buffer. If the buffer is too small the function returns an error and set the length to the size needed:

int CopyCppData(char * pszBuffer, int * ilength);