How would I include Psapi.h without running into a multiply included error?

Currently running into an issue where Winsock.h is already included in a header file elsewhere in my project...

Header not directly included:

# if defined(_WINSOCKAPI_) && !defined(_WINSOCK2API_)
# error WinSock.h has already been included
# endif // defined(_WINSOCKAPI_) && !defined(_WINSOCK2API_)

So that when I try to build, I get a the error "C1189 Winsock.h has already been included" (from the defined error message in the above piece of code).

However, I need to be able to use parts of the PSAPI to obtain memory usage information about the current process. I tried to include in my other file...

My .cpp File:

#include <Windows.h>
#include <Psapi.h>

...

SIZE_T getMemoryInfo() {    // The function that needs the includes

    PROCESS_MEMORY_COUNTERS pmc;
    SIZE_T memoryUsed;

    GetProcessMemoryInfo(GetCurrentProcess(), &pmc, sizeof(pmc));
    memoryUsed = pmc.WorkingSetSize;

    return memoryUsed;

}

After researching I then tried using WIN32_LEAN_AND_MEAN to try to get rid of the Winsock.h include, which works, but now when I try to use PROCESS_MEMORY COUNTERS I get an undefined symbol error...

"LNK2019 unresolved external symbol GetProcessMemoryInfo referenced in function..." and "LNK1120 1 unresolved externals [in myFile]"

I expect that I need to figure out how to include the actual header files I need, but the Windows docs do not say (and Wikipedia says that most of the child headers cannot be individually included, so that's probably an issue).

#define WIN32_LEAN_AND_MEAN
#include <Windows.h>    // Windows specific libraries for collecting software metrics.
#include <Psapi.h>

I've been trying to figure this out for a full day, any help would be appreciated as Windows Docs are pretty unhelpful and I am thoroughly frustrated. I apologize if it is a stupid question, but I frequently struggle with includes.

Solution

Finally figured it out.

Apparently the psapi.lib wasn't automatically being linked to by Visual Studio (despite the fact the Windows util libs are...). You have to go into properties/linker/input and manually add the library as a dependency. If it can't find the library location, add directory manually in C/C++ as a search directory.

You do have to have #define WIN32_LEAN_AND_MEAN as well.

Hope that helps, if anyone needs help with this in the future, just comment here.

Credit for the solution goes to @RbMn and @Scheff, thanks guys!