Linguagem C Média Escolar

#if defined(UNICODE) && !defined(_UNICODE)
    #define _UNICODE
#elif defined(_UNICODE) && !defined(UNICODE)
    #define UNICODE
#endif

#include <tchar.h>
#include <windows.h>
#include <math.h>
#include <stdio.h>
#include <memory.h>

#define BTN1 1
#define BTN2 2
#define BTN3 3

static HWND nome, nome2, num1, num2, num3, num4, resultado;

LRESULT CALLBACK WindowProcedure (HWND, UINT, WPARAM, LPARAM);

void addMenus(HWND);

HMENU hMenu;

TCHAR szClassName[ ] = _T("CodeBlocksWindowsApp");

int WINAPI WinMain (HINSTANCE hThisInstance, HINSTANCE hPrevInstance, LPSTR lpszArgument, int nCmdShow) {
    HWND       hwnd;        /* This is the handle for our window */
    MSG        messages;    /* Here messages to the application are saved */
    WNDCLASSEX wincl;       /* Data structure for the windowclass */

    wincl.hInstance     = hThisInstance;
    wincl.lpszClassName = szClassName;
    wincl.lpfnWndProc   = WindowProcedure;   /* This function is called by windows */
    wincl.style         = CS_DBLCLKS;        /* Catch double-clicks */
    wincl.cbSize        = sizeof (WNDCLASSEX);

    wincl.hIcon        = LoadIcon (NULL, IDI_QUESTION);
    wincl.hIconSm      = LoadIcon (NULL, IDI_QUESTION);
    wincl.hCursor      = LoadCursor (NULL, IDC_ARROW);
    wincl.lpszMenuName = NULL;                   /* No menu */
    wincl.cbClsExtra   = 0;                      /* No extra bytes after the window class */
    wincl.cbWndExtra   = 0;                      /* structure or the window instance */
    wincl.hbrBackground = GetSysColorBrush(COLOR_ACTIVECAPTION);

    /* Register the window class, and if it fails quit the program */
    if (!RegisterClassEx (&wincl))
        return 0;

    hwnd = CreateWindowEx (
        0, szClassName, _T("Media Escolar"), WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT, 600, 375,
        HWND_DESKTOP, NULL, hThisInstance, NULL
    );

    /* Make the window visible on the screen */
    ShowWindow (hwnd, nCmdShow);

    /* Run the message loop. It will run until GetMessage() returns 0 */
    while (GetMessage (&messages, NULL, 0, 0)) {
        TranslateMessage(&messages);
        DispatchMessage(&messages);
    }

    return messages.wParam;
}

LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam) {
    switch(message) {
        case WM_CREATE:
            addMenus(hwnd);

            nome = CreateWindowW(L"static", L"Calcular a Media de 4 Notas",
                                 WS_VISIBLE | WS_CHILD,
                                 10, 20, 260, 20,
                                 hwnd, NULL, NULL, NULL);

            CreateWindow(TEXT("button"), TEXT(" -> "), WS_VISIBLE | WS_CHILD,
                         10, 90, 80, 40, hwnd, (HMENU) BTN1, NULL, NULL);

            CreateWindow(TEXT("button"), TEXT("Site"), WS_VISIBLE | WS_CHILD,
                         110, 90, 160, 40,
                         hwnd, (HMENU) BTN2, NULL, NULL);

            nome2 = CreateWindowW(L"static", L"https://cgllp-mz.blogspot.com/",
                          WS_VISIBLE | WS_CHILD,
                          10, 180, 260, 20,
                          hwnd, NULL, NULL, NULL);

            CreateWindow(TEXT("static"), " C para Windows\n C para Linux\n C para App Móveis\n C Padrão ANSI", WS_VISIBLE | WS_CHILD,
                         340, 20, 180, 80,
                         hwnd, NULL, NULL, NULL);

            CreateWindowW(L"static", L"1 Nota: ",
                          WS_VISIBLE | WS_CHILD,
                          10, 220, 60, 20,
                          hwnd, NULL, NULL, NULL);

            num1 = CreateWindow(TEXT("edit"), TEXT(""), WS_VISIBLE | WS_CHILD | WS_BORDER,
                         74, 220, 50, 20,
                         hwnd, NULL, NULL, NULL);

            CreateWindowW(L"static", L"2 Nota: ",
                          WS_VISIBLE | WS_CHILD,
                          130, 220, 60, 20,
                          hwnd, NULL, NULL, NULL);

            num2 = CreateWindow(TEXT("edit"), TEXT(""), WS_VISIBLE | WS_CHILD | WS_BORDER,
                         196, 220, 50, 20,
                         hwnd, NULL, NULL, NULL);

            /**Cópia*/
            CreateWindowW(L"static", L"3 Nota: ",
                          WS_VISIBLE | WS_CHILD,
                          256, 220, 60, 20,
                          hwnd, NULL, NULL, NULL);

            num3 = CreateWindow(TEXT("edit"), TEXT(""), WS_VISIBLE | WS_CHILD | WS_BORDER,
                         322, 220, 50, 20,
                         hwnd, NULL, NULL, NULL);

            CreateWindowW(L"static", L"4 Nota: ",
                          WS_VISIBLE | WS_CHILD,
                          386, 220, 60, 20,
                          hwnd, NULL, NULL, NULL);

            num4 = CreateWindow(TEXT("edit"), TEXT(""), WS_VISIBLE | WS_CHILD | WS_BORDER,
                         452, 220, 50, 20,
                         hwnd, NULL, NULL, NULL);

            CreateWindow(TEXT("button"), TEXT("Calcular"), WS_VISIBLE | WS_CHILD | WS_BORDER,
                         10, 270, 100, 20,
                         hwnd, (HMENU) BTN3, NULL, NULL);

            CreateWindow(TEXT("static"), TEXT("Resultado:"), WS_VISIBLE | WS_CHILD,
                         160, 270, 100, 20,
                         hwnd, NULL, NULL, NULL);

            resultado = CreateWindow(TEXT("edit"), TEXT(""), WS_VISIBLE | WS_CHILD,
                         320, 270, 100, 20,
                         hwnd, NULL, NULL, NULL);
            break;
        case WM_COMMAND:
            if(LOWORD(wParam)==BTN1) {
                int len = GetWindowTextLength(nome)+1;
                static char title[500];
                GetWindowText(nome, title, len);
                MessageBox(NULL, title, "", MB_OK);
                return 0;
            }
            if(LOWORD(wParam)==BTN2) {
                int com = GetWindowTextLength(nome)+1;
                static char titulo[500];
                GetWindowText(nome2, titulo, com);
                MessageBox(NULL, titulo, "", MB_OK);
                return 0;
            }
            if(LOWORD(wParam)==BTN3) { /**Quando clicamos em calcular*/
                int n1 = GetWindowTextLength(num1)+1;
                int n2 = GetWindowTextLength(num2)+1;
                int n3 = GetWindowTextLength(num3)+1;
                int n4 = GetWindowTextLength(num4)+1;

                static char t1[50], t2[50], t3[50], t4[50];

                GetWindowText(num1, t1, n1);
                GetWindowText(num2, t2, n2);
                GetWindowText(num3, t3, n3);
                GetWindowText(num4, t4, n4);

                float res = (atof(t1)+atof(t2)+atof(t3)+atof(t4))/4;

                char tam[30];

                sprintf(tam, "%.2f", res);

                //ltoa(res, tam, 10);

                SetWindowText(resultado, tam);

                FILE *arq;
                arq=fopen("Teste.txt", "w+");
                fwrite(tam, sizeof(arq),10,arq);
                fclose(arq);
            }
            break;
        case WM_DESTROY:
            PostQuitMessage (0);       /* send a WM_QUIT to the message queue */
            break;
        default:                      /* for messages that we don't deal with */
            return DefWindowProc (hwnd, message, wParam, lParam);
    }

    return 0;
}

void addMenus(HWND hwnd) {

    hMenu = CreateMenu();

    HMENU hFileMenu = CreateMenu();

    AppendMenu(hMenu, MF_STRING, NULL, "Arquivo");
    AppendMenu(hMenu, MF_STRING, NULL, "Ajuda");
    AppendMenu(hMenu, MF_STRING, NULL, "Propriedade");
    AppendMenu(hMenu, MF_STRING, NULL, "Restart");
    AppendMenu(hMenu, MF_STRING, NULL, "Keyboard");

    SetMenu(hwnd, hMenu);

}