Getting response of a DLL in C - c++

Question

I've follow the next tutorial:
https://msdn.microsoft.com/en-us/library/64tkc9y5(v=vs.80).aspx
It is working fine for me. But I need to printf the response of the callbackfunctions:
printf(uReturnVal);
I get the error: cannot convert argument 1 from 'UINT' to 'const char *const '
I've tried another options:
printf(Convert.ToString(uReturnVal)); //ERROR :'Convert': undeclared identifier [
And:
printf(uReturnVal->ToString()); //ERROR: '->ToString' must point to class/struct/union/generic
And:
printf(uReturnVal.ToString());//error: /ERROR: '->ToString' must point to class/struct/union/generic
This is the code of the tutorial:
typedef UINT (CALLBACK* LPFNDLLFUNC1)(DWORD,UINT);
HINSTANCE hDLL; // Handle to DLL
LPFNDLLFUNC1 lpfnDllFunc1; // Function pointer
DWORD dwParam1;
UINT uParam2, uReturnVal;
hDLL = LoadLibrary("MyDLL");
if (hDLL != NULL)
{
lpfnDllFunc1 = (LPFNDLLFUNC1)GetProcAddress(hDLL,
"DLLFunc1");
if (!lpfnDllFunc1)
{
// handle the error
FreeLibrary(hDLL);
return true;
}
else
{
// call the function
uReturnVal = lpfnDllFunc1(dwParam1, uParam2);
}
}
Many thanks in advance.

Answer 1

First argument to printf functions is always format specifier. In your case printf("%u\n",uReturnVal) should work. See Format Specification Syntax: printf and wprintf Functions.
To Expand:
The code above is pure C.
You can also do it in C++ style, even more elegant:
#include <iostream>
...
uReturnVal = lpfnDllFunc1(dwParam1, uParam2);
std::cout << "Result is: " << uReturnVal << std::endl;