C# 讓TextBox只允許輸入數字

　　public class TextBoxEx : SystemWindowsFormsTextBox {

　　protected override void OnKeyPress(SystemWindowsFormsKeyPressEventArgs e) {

　　if (!charIsDigit(eKeyChar) && !eKeyCharEquals(\b) ) {

　　eHandled = true;

　　}

　　baseOnKeyPress(e);

　　}

　　}

From:http://tw.wingwit.com/Article/program/net/201311/12160.html