TextBox cancel event : TextBox « GUI Windows Forms « C# / CSharp Tutorial

1. C# / CSharp Tutorial
2. GUI Windows Forms
3. TextBox

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;

public class TextCancelEventKeyEvent : System.Windows.Forms.Form
{
  private System.Windows.Forms.Label label1;
  private System.Windows.Forms.TextBox txtInput;
  private System.Windows.Forms.Label label2;
  private System.Windows.Forms.Label lblTrue;
  private System.Windows.Forms.Label label3;
  private System.Windows.Forms.Label lblCheck;
    private System.Windows.Forms.Label lblResults;

  public TextCancelEventKeyEvent()
  {
    InitializeComponent();
  }

  private void InitializeComponent()
  {
     this.label1 = new System.Windows.Forms.Label();
     this.txtInput = new System.Windows.Forms.TextBox();
     this.label2 = new System.Windows.Forms.Label();
     this.lblTrue = new System.Windows.Forms.Label();
     this.label3 = new System.Windows.Forms.Label();
     this.lblCheck = new System.Windows.Forms.Label();
     this.lblResults = new System.Windows.Forms.Label();
     this.SuspendLayout();
     // 
     // label1
     // 
     this.label1.Font = new System.Drawing.Font("Tahoma", 14.25F, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic), System.Drawing.GraphicsUnit.Point, ((System.Byte)(0)));
     this.label1.Location = new System.Drawing.Point(48, 16);
     this.label1.Name = "label1";
     this.label1.Size = new System.Drawing.Size(176, 23);
     this.label1.TabIndex = 0;
     this.label1.Text = "ISBN Validation";
     // 
     // txtInput
     // 
     this.txtInput.Location = new System.Drawing.Point(72, 64);
     this.txtInput.Name = "txtInput";
     this.txtInput.TabIndex = 1;
     this.txtInput.Text = "";
     this.txtInput.KeyPress += new System.Windows.Forms.KeyPressEventHandler(this.txtInput_KeyPress);
     this.txtInput.Validating += new System.ComponentModel.CancelEventHandler(this.handleCancleEvent);
     // 
     // label2
     // 
     this.label2.Location = new System.Drawing.Point(24, 104);
     this.label2.Name = "label2";
     this.label2.Size = new System.Drawing.Size(80, 23);
     this.label2.TabIndex = 2;
     this.label2.Text = "True Number:";
     // 
     // lblTrue
     // 
     this.lblTrue.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D;
     this.lblTrue.Location = new System.Drawing.Point(112, 104);
     this.lblTrue.Name = "lblTrue";
     this.lblTrue.TabIndex = 3;
     // 
     // label3
     // 
     this.label3.Location = new System.Drawing.Point(32, 152);
     this.label3.Name = "label3";
     this.label3.Size = new System.Drawing.Size(72, 23);
     this.label3.TabIndex = 4;
     this.label3.Text = "Check Digit:";
     // 
     // lblCheck
     // 
     this.lblCheck.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D;
     this.lblCheck.Location = new System.Drawing.Point(112, 152);
     this.lblCheck.Name = "lblCheck";
     this.lblCheck.TabIndex = 5;
     // 
     // lblResults
     // 
     this.lblResults.Location = new System.Drawing.Point(56, 192);
     this.lblResults.Name = "lblResults";
     this.lblResults.Size = new System.Drawing.Size(152, 24);
     this.lblResults.TabIndex = 8;
     // 
     // TextCancelEventKeyEvent
     // 
     this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
     this.ClientSize = new System.Drawing.Size(264, 293);
     this.Controls.AddRange(new System.Windows.Forms.Control[] {
                                                                  this.lblResults,
                                                                  this.lblCheck,
                                                                  this.label3,
                                                                  this.lblTrue,
                                                                  this.label2,
                                                                  this.txtInput,
                                                                  this.label1});
     this.ResumeLayout(false);

  }
  [STAThread]
  static void Main() 
  {
    Application.Run(new TextCancelEventKeyEvent());
  }

  private void handleCancleEvent(object sender, System.ComponentModel.CancelEventArgs e)
  {
    TextBox tb = (TextBox)sender;
    string strInput = tb.Text;
        Console.WriteLine(strInput);
  }     

  private void txtInput_KeyPress(object sender, System.Windows.Forms.KeyPressEventArgs e)
  {
     char keyChar;
     keyChar = e.KeyChar;

     if(!Char.IsDigit(keyChar)      // 0 - 9
        &&
        keyChar != 8               // backspace
        &&
        keyChar != 13              // enter
        &&
        keyChar != 'x'
        &&
        keyChar != 45              //  dash/minus
        ){
        //  Do not display the keystroke
        e.Handled = true;
     }
  }     
}

23.17.TextBox
	23.17.1.	Get input value from TextBox and display it vis a messagebox
	23.17.2.	TextBox key pressed event
	23.17.3.	TextBox Modified and TextChanged
	23.17.4.	TextBox: Multiline and BorderStyle
	23.17.5.	TextBox Keyevent hander
	23.17.6.	TextBox cancel event
	23.17.7.	Count lines in the TextBox and read text in TextBox line by line
	23.17.8.	TextBox selection
	23.17.9.	TextBox validation
	23.17.10.	Add ContextMenu to TextBox
	23.17.11.	Use Regular Expression to Check the input for a TextBox
	23.17.12.	Multiline TextBox
	23.17.13.	Simple Editor