Win32 API application glitching

Question

I am new to the Win32 API, and I tried making my own calculator, but when I run the code, the edit control starts to glitch, and I can't see what has been inputted.

I tried adding a button which stores the value 1 into the edit control (where the text of the calculator will be displayed), but whenever I use the button, or try to type directly, the text starts to glitch.

#include <windows.h>
#include <stdlib.h>

#define ONE_BUTTON 1
/*#define TWO_BUTTON 2
#define THREE_BUTTON 3
#define FOUR_BUTTON 4
#define FIVE_BUTTON 5
#define SIX_BUTTON 6
#define SEVEN_BUTTON 7
#define EIGHT_BUTTON 8
#define NINE_BUTTON 9
#define TEN_BUTTON 0*/




void AddControls(HWND);

HWND hOut;

HWND hOne;

LRESULT CALLBACK WindowProcedure(HWND,UINT,WPARAM,LPARAM);
int WINAPI WinMain(HINSTANCE hInst, HINSTANCE hPrevInst , LPSTR args, int ncmdshow)
{
    WNDCLASSW wc = {0};
    wc.hbrBackground = (HBRUSH)COLOR_WINDOW;
    wc.hCursor = LoadCursor(NULL,IDC_ARROW);
    wc.hInstance = hInst;
    wc.lpszClassName = L"mywindowclass";
    wc.lpfnWndProc = WindowProcedure;
    if(!RegisterClassW(&wc))
        return -1;

    CreateWindowW(L"mywindowclass",L"calculatorGUi",WS_OVERLAPPEDWINDOW|WS_VISIBLE,100,100,500,350,NULL,NULL,NULL,NULL);

    MSG msg = {0};
    while(GetMessage(&msg,NULL,NULL,NULL))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

}
LRESULT CALLBACK WindowProcedure(HWND hWnd,UINT msg,WPARAM wp,LPARAM lp)
{
    switch(msg)
    {
    case WM_COMMAND:
        switch (wp)
        {
        case ONE_BUTTON:
            char one[50];
            char out[15];
            GetWindowText(hOne,one,50);

            strcpy(out,one);

            SetWindowText(hOut,out);
        }


    case WM_CREATE:
        AddControls(hWnd);
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
    default:
        return DefWindowProcW(hWnd,msg,wp,lp);
    }
}

void AddControls(HWND hWnd)
{
    hOut = CreateWindowW(L"Edit",(int)NULL,WS_VISIBLE|WS_CHILD|WS_BORDER,2,2,480,106,hWnd,NULL,NULL,NULL);

    hOne= CreateWindowW(L"Button",L"1",WS_VISIBLE|WS_CHILD|BS_RADIOBUTTON|BS_DEFPUSHBUTTON 2,110,98,50,hWnd,(HMENU)ONE_BUTTON,NULL,NULL);

    /*CreateWindowW(L"Button",L"2",WS_VISIBLE|WS_CHILD,102,110,99,50,hWnd,(HMENU)TWO_BUTTON,NULL,NULL);
    CreateWindowW(L"Button",L"3",WS_VISIBLE|WS_CHILD,202,110,99,50,hWnd,(HMENU)THREE_BUTTON,NULL,NULL);
    CreateWindowW(L"Button",L"4",WS_VISIBLE|WS_CHILD,302,110,99,50,hWnd,(HMENU)FOUR_BUTTON,NULL,NULL);
    CreateWindowW(L"Button",L"5",WS_VISIBLE|WS_CHILD,402,110,80,50,hWnd,(HMENU)FIVE_BUTTON,NULL,NULL);

    CreateWindowW(L"Button",L"6",WS_VISIBLE|WS_CHILD,2,165,99,50,hWnd,(HMENU)SIX_BUTTON,NULL,NULL);
    CreateWindowW(L"Button",L"7",WS_VISIBLE|WS_CHILD,102,165,99,50,hWnd,(HMENU)SEVEN_BUTTON,NULL,NULL);
    CreateWindowW(L"Button",L"8",WS_VISIBLE|WS_CHILD,202,165,99,50,hWnd,(HMENU)EIGHT_BUTTON,NULL,NULL);
    CreateWindowW(L"Button",L"+",WS_VISIBLE|WS_CHILD,302,165,99,50,hWnd,(HMENU)NINE_BUTTON,NULL,NULL);
    CreateWindowW(L"Button",L"-",WS_VISIBLE|WS_CHILD,402,165,99,50,hWnd,(HMENU)TEN_BUTTON,NULL,NULL);

    CreateWindowW(L"Button",L"9",WS_VISIBLE|WS_CHILD,2,220,99,50,hWnd,NULL,NULL,NULL);
    CreateWindowW(L"Button",L"0",WS_VISIBLE|WS_CHILD,102,220,99,50,hWnd,NULL,NULL,NULL);
    CreateWindowW(L"Button",L"*",WS_VISIBLE|WS_CHILD,202,220,99,50,hWnd,NULL,NULL,NULL);
    CreateWindowW(L"Button",L"/",WS_VISIBLE|WS_CHILD,302,220,99,50,hWnd,NULL,NULL,NULL);
    CreateWindowW(L"Button",L"=",WS_VISIBLE|WS_CHILD,402,220,99,50,hWnd,NULL,NULL,NULL);*/


}

Answer 1

Your WM_COMMAND and ONE_BUTTON cases are both missing break statements, so whenever the Edit sends update notifications to your main window, or whenever the button is clicked, your code falls through to call AddControls(), creating more and more child controls on top of the previous child controls, and reusing the same child IDs.

Also, your ONE_BUTTON handler has a buffer overflow if the user enters text with more than 14 characters.

Try this instead:

LRESULT CALLBACK WindowProcedure(HWND hWnd, UINT msg, WPARAM wp, LPARAM lp)
{
    switch(msg)
    {
    case WM_COMMAND:
        switch (wp)
        {
        case ONE_BUTTON: {
            char one[50] = {};
            GetWindowText(hOne, one, 50);
            SetWindowText(hOut, one);
            break; // <-- add this!
        }
        break; // <-- add this!

    case WM_CREATE:
        AddControls(hWnd);
        break;

    case WM_DESTROY:
        PostQuitMessage(0);
        break; // <-- add this!

    default:
        return DefWindowProcW(hwnd, msg, wp, lp);
    }

    return 0; // <-- add this!
}