Data validation

CSharp kode 

 <Window x:Class="WPFWxample.FormValidation"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         Title="FormValidation" Height="300" Width="300">
     <Window.Resources>
         <src:Customer x:Key="Emp"></src:Customer>
 
         <!--The Too tip for the textbox-->
         <Style x:Key="txterror" TargetType="{x:Type TextBox}">
             <Style.Triggers>
                 <Trigger Property="Validation.HasError" Value="true">
                     <Setter Property="ToolTip"
              Value="{Binding RelativeSource={x:Static RelativeSource.Self},
               Path=(Validation.Errors)[0].ErrorContent}"></Setter>
                     <Setter Property="Background" Value="Red"></Setter>
                 </Trigger>
             </Style.Triggers>
         </Style>
     </Window.Resources>
 
     <Grid>
         <Label Height="28" HorizontalAlignment="Left" Margin="12,27,0,0"
       Name="label1" VerticalAlignment="Top" Width="151">Emp. No</Label>
         <TextBox Height="23"
              Margin="262,27,96,0"
              Name="txteno"
              VerticalAlignment="Top" Style="{StaticResource txterror}">
             <TextBox.Text>
                 <Binding Path="EmpNo" Source="{StaticResource Emp}"
                       ValidatesOnDataErrors="True"
                       UpdateSourceTrigger="PropertyChanged">
                     <Binding.ValidationRules>
                         <ExceptionValidationRule></ExceptionValidationRule>
                     </Binding.ValidationRules>
                 </Binding>
             </TextBox.Text>
         </TextBox>
         <Label Height="28" HorizontalAlignment="Left" Margin="12,72,0,0"
       Name="label2" VerticalAlignment="Top" Width="151">Emp. Name</Label>
         <Label HorizontalAlignment="Left" Margin="12,122,0,112" Name="label3"
            Width="151">Salary</Label>
         <TextBox Height="23" Margin="262,74,96,0" Name="txtename"
              VerticalAlignment="Top" Style="{StaticResource txterror}">
             <TextBox.Text>
                 <Binding Path="EmpName" Source="{StaticResource Emp}"
                       ValidatesOnDataErrors="True"
                       UpdateSourceTrigger="PropertyChanged">
                     <Binding.ValidationRules>
                         <ExceptionValidationRule></ExceptionValidationRule>
                     </Binding.ValidationRules>
                 </Binding>
             </TextBox.Text>
         </TextBox>
         <TextBox Margin="262,127,96,112" Name="txtsal"
              Style="{StaticResource txterror}">
             <TextBox.Text>
                 <Binding Path="Salary" Source="{StaticResource Emp}"
                       ValidatesOnDataErrors="True"
                       UpdateSourceTrigger="PropertyChanged">
                     <Binding.ValidationRules>
                         <ExceptionValidationRule></ExceptionValidationRule>
                     </Binding.ValidationRules>
                 </Binding>
             </TextBox.Text>
         </TextBox>
         <Button Height="23" Margin="12,0,96,55" Name="button1"
             VerticalAlignment="Bottom">Button</Button>
     </Grid>
 </Window>

CSharp kode 

 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 
 namespace WPFWxample
 {
     
         public class Customer : IDataErrorInfo
         {
             private int _EmpNo;
 
             public int EmpNo
             {
                 get { return _EmpNo; }
                 set { _EmpNo = value; }
             }
             private string _EmpName = "";
 
             public string EmpName
             {
                 get { return _EmpName; }
                 set { _EmpName = value; }
             }
             private int _Salary;
 
             public int Salary
             {
                 get { return _Salary; }
                 set { _Salary = value; }
             }
 
             #region IDataErrorInfo Members
 
             public string Error
             {
                 get { return null; }
             }
 
             public string this[string fieldName]
             {
                 get
         {
             string result = null;
 
             #region For Validating EmpNo
             if (fieldName == "EmpNo")
             {
                 if (this._EmpNo < 0)
                 {
                     result = "Emp No should not be less than 0";
                 }
             }
             #endregion
 
             #region For Validating EmpName
             if (fieldName == "EmpName")
             {
                 if (this._EmpName == string.Empty)
                 {
                     result = "Employee Name should not be blank";
                 }
                 else
                 {
                     foreach (char c in this._EmpName)
                     {
                         if (c < 65  c > 122  (c >= 91 && c <= 96))
                         {
                             result = "Employee Name should " +
                                 "not Contain Special Characters";
                         }
                     }
                 }
             }
             #endregion
 
             #region For Validating Salary
             if (fieldName == "Salary")
             {
                 if (this._Salary < 0)
                 {
                     result = "Salary should not be less than Zero";
                 }
             }
             #endregion
 
             return result;
         }
             }
 
             #endregion
         }
     }