WinAPI - show key pressed - c++

Question

I'm trying to learn WinAPI programming but now I got stuck with this problem - I want to get pressed key and show it. I have this piece of code
LRESULT CALLBACK WndProc(HWND hwnd, UINT Msg, WPARAM wParam, LPARAM lParam){
switch(Msg){
case WM_CREATE:
break;
case WM_CHAR:
char ascii_code = wParam;
unsigned int key_state = lParam;
SetWindowText(hwndStatic, TEXT("You pressed key "+ascii_code));
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
}
return DefWindowProc(hwnd, Msg, wParam, lParam);
}
but the output is weird... It shows random messages(different for each key). What am I doing wrong?
I tried to debug it (step by step) and the ascii_code contains the pressed key but the TEXT() doesn't show it.

Answer 1

You can't add characters together like this:
"You pressed key "+ascii_code;
This will take the address of "You pressed key ", e.g. 1000 and add the ascii code value to it, e.g. 95.
The function will try to print the string at memory address 1095. It will print all the memory until it hits a null character (zero). This could be anything.
You need to either use C functions to build your string, or, as this is tagged C++ use std::string.
std::string message = "You pressed key ";
message += ascii_code;
SetWindowText(hwndStatic, TEXT(message.c_str()))

Answer 2

"You pressed key "+ascii_code
You cannot concatenate strings like that. The real type of "foo bar" is const char[8] - a raw C-like array of characters. When you apply + on it, it decays to a pointer to its first element and the operation is carried on the pointer. This means you end up printing some random data based on where this pointer ends up pointing in the end.
If you want to concatenate a character to a string, you have to use more intelligent string representation, such as std::string:
(std::string("you pressed key ") + ascii_code).c_str();