使用Labwindows设计的用户登录界面如何实现输入的密码显示为*****

要在LabWindows中实现输入密码时显示星号（*），可以使用Windows API函数来实现。以下是一个示例代码段，可以在密码框中输入字符并将其显示为星号。

#include <windows.h>
#include <stdio.h>

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

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
    LPSTR lpCmdLine, int nCmdShow)
{
    static char szAppName[] = "PasswordDemo";
    HWND hwnd;
    MSG msg;
    WNDCLASS wndclass;

    wndclass.style = CS_HREDRAW | CS_VREDRAW;
    wndclass.lpfnWndProc = WndProc;
    wndclass.cbClsExtra = 0;
    wndclass.cbWndExtra = 0;
    wndclass.hInstance = hInstance;
    wndclass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    wndclass.hCursor = LoadCursor(NULL, IDC_ARROW);
    wndclass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
    wndclass.lpszMenuName = NULL;
    wndclass.lpszClassName = szAppName;

    if (!RegisterClass(&wndclass))
    {
        MessageBox(NULL, "This program requires Windows NT!", szAppName, MB_ICONERROR);
        return 0;
    }

    hwnd = CreateWindow(szAppName, "Password Demo",
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT,
        CW_USEDEFAULT, CW_USEDEFAULT,
        NULL, NULL, hInstance, NULL);

    ShowWindow(hwnd, nCmdShow);
    UpdateWindow(hwnd);

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

    return msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    static HWND hwndEdit;
    static char szPassword[64];
    int iLength;

    switch (message)
    {
    case WM_CREATE:
        hwndEdit = CreateWindow("EDIT", "",
            WS_CHILD | WS_VISIBLE | WS_BORDER | ES_PASSWORD,
            10, 10, 200, 25,
            hwnd, (HMENU)1, ((LPCREATESTRUCT)lParam)->hInstance, NULL);
        break;

    case WM_COMMAND:
        if (LOWORD(wParam) == 1 && HIWORD(wParam) == EN_CHANGE)
        {
            iLength = GetWindowText(hwndEdit, szPassword, sizeof(szPassword));
            if (iLength > 0)
            {
                printf("Password: %s\n", szPassword);
            }
        }
        break;

    case WM_DESTROY:
        PostQuitMessage(0);
        break;

    default:
        return DefWindowProc(hwnd, message, wParam, lParam);
    }
    return 0;
}

在上面的示例代码中，我们在创建密码框时使用了ES_PASSWORD样式，这样在密码框中输入的字符就会被显示为星号。当用户在密码框中输入字符时，程序会检测EN_CHANGE消息，并使用GetWindowText函数获取密码框中的文本，然后在控制台中输出密码。