说明：
c#使用windows forms app实现helloworld和login登录
效果图：
step1:登录 C:\Users\wangrusheng\RiderProjects\WinFormsApp1\WinFormsApp1\Form1.cs
namespace WinFormsApp1;public partial class Form1 : Form
{private TextBox txtUsername;private TextBox txtPassword;private Label lblError;public Form1(){InitializeComponent();CreateLoginControls();}private void CreateLoginControls(){// 窗口配置this.Text = "用户登录";this.ClientSize = new Size(800, 600);this.StartPosition = FormStartPosition.CenterScreen; // 屏幕居中// 使用Panel容器统一管理布局Panel mainPanel = new Panel();mainPanel.Size = new Size(400, 300);mainPanel.Location = new Point((this.ClientSize.Width - mainPanel.Width) / 2,(this.ClientSize.Height - mainPanel.Height) / 2);// 用户名标签Label lblUser = new Label();lblUser.Text = "用户名：";lblUser.Font = new Font("微软雅黑", 12F);lblUser.Location = new Point(50, 40);lblUser.AutoSize = true;// 用户名输入框（加宽）txtUsername = new TextBox();txtUsername.Font = new Font("微软雅黑", 12F);txtUsername.Location = new Point(50, 70);txtUsername.Size = new Size(300, 30); // 宽度300// 密码标签Label lblPass = new Label();lblPass.Text = "密 码：";lblPass.Font = new Font("微软雅黑", 12F);lblPass.Location = new Point(50, 130);lblPass.AutoSize = true;// 密码输入框（与用户名对齐）txtPassword = new TextBox();txtPassword.Font = new Font("微软雅黑", 12F);txtPassword.Location = new Point(50, 160);txtPassword.Size = new Size(300, 30);txtPassword.PasswordChar = '●';// 登录按钮（加大尺寸）Button btnLogin = new Button();btnLogin.Text = "登 录";btnLogin.Font = new Font("微软雅黑", 12F, FontStyle.Bold);btnLogin.Size = new Size(300, 40);btnLogin.Location = new Point(50, 210);btnLogin.BackColor = Color.DodgerBlue;btnLogin.ForeColor = Color.White;btnLogin.Click += BtnLogin_Click;// 错误提示（居中显示）lblError = new Label();lblError.ForeColor = Color.Red;lblError.Font = new Font("微软雅黑", 10F);lblError.AutoSize = true;lblError.Location = new Point((mainPanel.Width - lblError.Width) / 2,260);lblError.Visible = false;// 添加控件到PanelmainPanel.Controls.AddRange(new Control[] {lblUser, txtUsername,lblPass, txtPassword,btnLogin, lblError});// 添加Panel到窗体this.Controls.Add(mainPanel);}private void BtnLogin_Click(object sender, EventArgs e){// 错误提示自动居中lblError.Location = new Point((this.Controls[0].Width - lblError.Width) / 2,lblError.Location.Y);// 简单验证逻辑if (string.IsNullOrEmpty(txtUsername.Text) || string.IsNullOrEmpty(txtPassword.Text)){lblError.Text = "用户名和密码不能为空！";lblError.Visible = true;return;}// 模拟验证（实际应连接数据库）if (txtUsername.Text == "admin" && txtPassword.Text == "123456"){lblError.Visible = false;MessageBox.Show("登录成功！");// 此处可跳转到主窗体：new MainForm().Show();}else{lblError.Text = "用户名或密码错误！";lblError.Visible = true;}}}
step2：helloworld
namespace WinFormsApp1;public partial class Form1 : Form
{public Form1(){InitializeComponent();// 添加Label控件Label label = new Label();label.Text = "Hello World!";label.AutoSize = true; // 自动调整标签大小label.Location = new System.Drawing.Point(20, 20); // 设置位置this.Controls.Add(label); // 将标签添加到窗体}
}
end