C++如何写一个控制台登陆窗口的代码，同时密码和用户名需要和本地的数据库中的用户表进行校验

实现控制台登陆窗口需要使用Windows API函数和C++的标准库。以下是一个简单的实现过程：

1. 引入头文件

#include <iostream>
#include <string>
#include <Windows.h>
#include <mysql.h> // MySQL数据库相关头文件，需要自行安装MySQL C++ Connector

2. 定义数据库连接

MYSQL* conn;
conn = mysql_init(NULL);
mysql_real_connect(conn, "localhost", "root", "password", "database_name", 0, NULL, 0);

3. 定义用户输入的用户名和密码

std::string username;
std::string password;

4. 绘制登陆窗口

HWND hwnd = GetConsoleWindow();
HDC hdc = GetWindowDC(hwnd);
RECT rect;
GetWindowRect(hwnd, &rect);
int width = rect.right - rect.left;
int height = rect.bottom - rect.top;
int x = (GetSystemMetrics(SM_CXSCREEN) - width) / 2;
int y = (GetSystemMetrics(SM_CYSCREEN) - height) / 2;
SetWindowPos(hwnd, HWND_TOP, x, y, width, height, SWP_SHOWWINDOW);
system("cls");
std::cout << "Username: ";
std::getline(std::cin, username);
std::cout << "Password: ";
std::getline(std::cin, password);

5. 查询数据库并校验用户名和密码

std::string query = "SELECT * FROM users WHERE username='" + username + "' AND password='" + password + "'";
const char* q = query.c_str();
mysql_query(conn, q);
MYSQL_RES* res = mysql_store_result(conn);
int num_fields = mysql_num_fields(res);
MYSQL_ROW row;
if (mysql_num_rows(res) == 0) {
    std::cout << "Invalid username or password" << std::endl;
} else {
    std::cout << "Login successful!" << std::endl;
}

6. 关闭数据库连接和释放资源

mysql_free_result(res);
mysql_close(conn);

完整代码：

#include <iostream>
#include <string>
#include <Windows.h>
#include <mysql.h>

int main() {
    MYSQL* conn;
    conn = mysql_init(NULL);
    mysql_real_connect(conn, "localhost", "root", "password", "database_name", 0, NULL, 0);
    std::string username;
    std::string password;
    HWND hwnd = GetConsoleWindow();
    HDC hdc = GetWindowDC(hwnd);
    RECT rect;
    GetWindowRect(hwnd, &rect);
    int width = rect.right - rect.left;
    int height = rect.bottom - rect.top;
    int x = (GetSystemMetrics(SM_CXSCREEN) - width) / 2;
    int y = (GetSystemMetrics(SM_CYSCREEN) - height) / 2;
    SetWindowPos(hwnd, HWND_TOP, x, y, width, height, SWP_SHOWWINDOW);
    system("cls");
    std::cout << "Username: ";
    std::getline(std::cin, username);
    std::cout << "Password: ";
    std::getline(std::cin, password);
    std::string query = "SELECT * FROM users WHERE username='" + username + "' AND password='" + password + "'";
    const char* q = query.c_str();
    mysql_query(conn, q);
    MYSQL_RES* res = mysql_store_result(conn);
    int num_fields = mysql_num_fields(res);
    MYSQL_ROW row;
    if (mysql_num_rows(res) == 0) {
        std::cout << "Invalid username or password" << std::endl;
    } else {
        std::cout << "Login successful!" << std::endl;
    }
    mysql_free_result(res);
    mysql_close(conn);
    return 0;
}

需要注意的是，这只是一个简单的示例代码，实际使用时需要考虑安全性和用户体验等问题。