C#教程：KeyPress事件使用实例|方法
KeyPress事件
KeyPress事件在用户完成按键后发生。
示例
KeyPress事件的使用
本示例中，当程序运行时，只允许在文本框中输入数字，如果文本框输入的内容不是数字，文本框中的内容会显示在窗体的标题栏上，文本框中不会显示内容。示例运行结果如图1所示。
图1 KeyPress事件的使用
private void textBox2_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar != 8 && !char.IsDigit(e.KeyChar))
{
this.Text = e.KeyChar.ToString();
e.Handled = True;
}
}
完整程序代码如下：
★ ★★★★frmKepress.cs窗体代码文件完整程序代码★★★★★
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
namespace _2_09
{
public partial class frmKepress : Form
{
public frmKepress()
{
InitializeComponent();
}
private void frmKepress_Load(object sender, EventArgs e)
{
}
private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
this.Text = e.KeyChar.ToString();
e.Handled = true;
}
private void frmKepress_Load_1(object sender, EventArgs e)
{
}
private void textBox2_KeyPress(object sender, KeyPressEventArgs e)
{
if (e.KeyChar != 8 && !char.IsDigit(e.KeyChar))
{
this.Text = e.KeyChar.ToString();
e.Handled = true;
}
}
}
}
★ ★★★★frmKepress.desiger.cs窗体设计文件完整程序代码★★★★★
namespace _2_09
{
partial class frmKepress
{
///
/// 必需的设计器变量。
///
private System.ComponentModel.IContainer components = null;
///
/// 清理所有正在使用的资源。
///
/// 如果应释放托管资源，为 true；否则为 false。
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}
#region Windows 窗体设计器生成的代码
///
/// 设计器支持所需的方法 - 不要
/// 使用代码编辑器修改此方法的内容。
///
private void InitializeComponent()
{
this.textBox1 = new System.Windows.Forms.TextBox();
this.textBox2 = new System.Windows.Forms.TextBox();
this.label1 = new System.Windows.Forms.Label();
this.SuspendLayout();
//
// textBox1
//
this.textBox1.Location = new System.Drawing.Point(53, 80);
this.textBox1.Name = "textBox1";
this.textBox1.Size = new System.Drawing.Size(151, 21);
this.textBox1.TabIndex = 0;
//
// textBox2
//
this.textBox2.Location = new System.Drawing.Point(144, 35);
this.textBox2.Name = "textBox2";
this.textBox2.Size = new System.Drawing.Size(100, 21);
this.textBox2.TabIndex = 0;
this.textBox2.KeyPress += new System.Windows.Forms.KeyPressEventHandler(this.textBox2_KeyPress);
//
// label1
//
this.label1.AutoSize = true;
this.label1.Location = new System.Drawing.Point(46, 38);
this.label1.Name = "label1";
this.label1.Size = new System.Drawing.Size(77, 12);
this.label1.TabIndex = 1;
this.label1.Text = "请输入数字：";
//
// frmKepress
//
this.ClientSize = new System.Drawing.Size(292, 105);
this.Controls.Add(this.label1);
this.Controls.Add(this.textBox2);
this.Name = "frmKepress";
this.Text = "请输入数字";
this.Load += new System.EventHandler(this.frmKepress_Load_1);
this.ResumeLayout(false);
this.PerformLayout();
}
#endregion
private System.Windows.Forms.TextBox textBox1;
private System.Windows.Forms.TextBox textBox2;
private System.Windows.Forms.Label label1;
}
}
★ ★★★★Program.cs主程序文件完整程序代码★★★★★
using System;
using System.Collections.Generic;
using System.Windows.Forms;
namespace _2_09
{
static class Program
{
///
/// 应用程序的主入口点。
///
[STAThread]