How can I make integer to display in window? - winapi

Question

I want to have in window something like:
int a;
cout<<a;
but I don't know how I can do it. At the beginning, I want to have number displayed on screen and have a button which adds +1 and another button which adds -1 to this number. I want this number to be updated without next compilation. Do you know how I can do it?
I want it to be a prototype of simple calculator.

Answer 1

You can do your calculation in your corresponding button handler and set the "screen's" text with SetWindowText message.
The idea is following:
You have 2 buttons-one to add and one to subtract. You can create them in your WM_CREATE handler like this:
case WM_CREATE:
{
HWND btnAdd = CreateWindowEx( 0, L"Button",
L"+1", //this is the text for your adding button
WS_CHILD | WS_VISIBLE | WS_BORDER | BS_PUSHBUTTON,
50, 150, 150, 25, hWnd, (HMENU)8004, hInst, 0 );
HWND btnSubtract = CreateWindowEx( 0, L"Button",
L"-1", //this is the text for your adding button
WS_CHILD | WS_VISIBLE | WS_BORDER | BS_PUSHBUTTON,
50, 250, 150, 25, hWnd, (HMENU)8005, hInst, 0 );
// since you want "calculator type" application
// here is your result window-edit control
HWND input = CreateWindowEx( 0, L"Edit",
L"", // no need for text
WS_CHILD | WS_VISIBLE | WS_BORDER | ES_NUMBER | ES_AUTOHSCROLL,
50, 450, 150, 25, hWnd, (HMENU)8006, hInst, 0 );
HWND result = CreateWindowEx( 0, L"Edit",
L"", // no need for text
WS_CHILD | WS_VISIBLE | WS_BORDER | ES_READONLY | ES_AUTOHSCROLL,
50, 450, 150, 25, hWnd, (HMENU)8007, hInst, 0 );
// other stuff
}
return 0L;
After user clicks on your buttons you set text of the result edit control with SetWindowText like this in your WM_COMMAND handler:
case 8004: // add 1 to the number
{
// get the number from input edit control
wchar_t temp[10];
GetWindowText( GetDlgItem( hWnd, 8006 ), temp, 10 );
//convert text to nubmer
int InputedNumber = wtoi( temp );
// show the result in the result edit control
memset( temp, L'\0', sizeof(temp) ); //reuse variable to save memory
swprintf_s( temp, 10, L"%d", InputNumber+1 ); //convert result to text
SetWindowText( GetDlgItem( hWnd, 8007 ), temp ); //show the result
}
case 8005: // subtract 1 to the number
{
// get the number from input edit control
wchar_t temp[10];
GetWindowText( GetDlgItem( hWnd, 8006 ), temp, 10 );
//convert text to number
int InputedNumber = wtoi( temp );
// show the result in the result edit control
memset( temp, L'\0', sizeof(temp) ); //reuse variable to save memory
swprintf_s( temp, 10, L"%d", InputNumber-1 ); //convert result to text
SetWindowText( GetDlgItem( hWnd, 8007 ), temp ); //show the result
}
Above were relevant code snippets for C++.
This might be a big bite for you to handle, so I recommend you to go through this beginner tutorial.
Good luck and best regards!