How to dynamically load every needed function

Question

I'm trying to find a way to dynamically load every Windows API function I need to use. For example, to use a the printf function, I do something like:

#include <windows.h>

typedef int (*printfPtr)(const char *str, ...);
int main(){
    HMODULE handle = LoadLibraryA("crtdll.dll");
    if(handle == NULL) return;
    printfPtr printfAdr = (printfPtr)GetProcAddress(handle, "printf");
    (*printfAdr)("This is a test\n");
}

This is a fast coded working snippet. Doing this was easy because I followed a guide which told me that I could load the printf from the crtdll.dll. However, now I would like to load the CreateFileA function but I don't know how to find the correct dll to load.

I've already tried to Google something and searched on the MSDN but I didn't find anything. In general, given one function (a common one, for example one in windows.h, stdio.h or stdlib.h), how can I find which dll to load?

N.B. I know that some of you may think that loading function this way as no use. However, this is not the real program. In the real one, the addresses LoadLibraryA and GetProcAddress are manually found and I can write code and then export the segment from the PE.

Your search on MSDN wasn't very thorough, because the "Requirements" table at the bottom of [the official `CreateFileA` page](https://learn.microsoft.com/en-us/windows/desktop/api/fileapi/nf-fileapi-createfilea) says (in addition to Minimum Windows Version, Header File, and Import Library) "DLL: kernel32.dll" — Ben Voigt, Sep 12 '18 at 17:27
Yeah, i found it later, anyway the question didn't change, i needed a way to find dlls for all the function i need and they gave it to me — Luca Reccia, Sep 12 '18 at 17:40
FYI, crtdll.dll is a legacy DLL that's only included in SysWOW64 for 32-bit programs. It's not available for 64-bit programs. The version I have in Windows 10 is from 9 Dec 1995, based on the timestamp in the PE header. — Eryk Sun, Sep 12 '18 at 17:50

score 1 · Accepted Answer · answered Sep 12 '18 at 17:29

The function in your example (printf) is not a Windows API function, rather it is a function defined in the C standard. Therefore it should be more readily available. However this re-enforces the point that if you don't have any of the either standard or Windows API functions available that makes for a lot of dlls to know about. I don't know of a single place that defines them all in one source file, but you can load your functions on a case by case basis using a resource like www.pinvoke.net which lets you type in a function name and retrieve the name of the dll to load (as well as the C# method signature but you don't need that, you already know the C signature).

How to dynamically load every needed function

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