Unable to find an entry point - c++-cli

Question

I import two WinApi functions and use them in my class
using namespace System::Runtime::InteropServices;
[DllImport("user32",ExactSpelling = true)]
extern bool CloseWindow(int hwnd);
[DllImport("user32",ExactSpelling = true)]
extern int FindWindow(String^ classname,String^ windowname);
public ref class WinApiInvoke
{
public:
bool CloseWindowCall(String^ title)
{
int pointer = FindWindow(nullptr,title);
return CloseWindow(pointer);
}
};
Then I create object in main program and call CloseWindowCall method
Console::WriteLine("Window's title");
String ^s = Console::ReadLine();
WinApiInvoke^ obj = gcnew WinApiInvoke();
if (obj->CloseWindowCall(s))
Console::WriteLine("Window successfully closed!");
else Console::WriteLine("Some error occured!");
When I write in console for example Chess Titans to close I've got an error
Unable to find an entry point named 'FindWindow' in DLL 'user32'
What entry point?

Answer 1

You are using the ExactSpelling property inappropriately. There is no FindWindow function in user32.dll, just like the exception message says. There is FindWindowA and FindWindowW. The first one handles legacy 8-bit character strings, the second uses Unicode strings. Any Windows api function that accepts strings has two versions, you don't see this in C or C++ code because the UNICODE macro selects between the two.
Avoid ExactSpelling on winapi functions, the pinvoke marshaller knows how to deal with this. You have some other mistakes, the proper declaration is:
[DllImport("user32.dll", CharSet = CharSet::Auto, SetLastError = true)]
static IntPtr FindWindow(String^ classname, String^ windowname);