dll programming question.

[time to c]

so i tried to compile dll and use it with another console application.
the attempt was successful but i didn't under stood few things in the code given below can someone explain them??

#include<windows.h>

typedef void (*hello_ptr) ();

hello_ptr hello = NULL;

int APIENTRY WinMain(HINSTANCE,HINSTANCE,LPSTR,int)
{
    HMODULE mydll = LoadLibrary("mydll.dll");
    if(mydll)
    {
        hello = (hello_ptr) GetProcAddress(mydll,"hello");
        if(hello)
        {
            hello();
            FreeLibrary(mydll);
        }
    }
    return 0;
}

as you know by looking at code it loads hello function from a dll file mydll.dll.
in this code i didn't understood this things.

typedef void (*hello_ptr) ();

hello_ptr hello = NULL;

what is exactly happening here??

and

int APIENTRY WinMain(HINSTANCE,HINSTANCE,LPSTR,int)

same question what this line is doing??

[webJose]

The typedef is a type definition that defines hello_ptr as a function pointer type compatible with functions that return nothing (void) and take no arguments.

The second line declares a variable of type hello_ptr.

WinMain is an application's entry point in the CRT for Windows GUI applications. It is the equivalent of main() for console applications.

[time to c]

Thanks for helping.