BaseCompareValidator.CanConvert Method (String, ValidationDataType)
Determines whether the specified string can be converted to the specified data type. This version of the overloaded method tests currency, double, and date values using the format used by the current culture.
Assembly: System.Web (in System.Web.dll)
Public Shared Function CanConvert ( text As String, type As ValidationDataType ) As Boolean
Parameters
- text
-
Type:
System.String
The string to test.
- type
-
Type:
System.Web.UI.WebControls.ValidationDataType
One of the ValidationDataType values.
Return Value
Type: System.Booleantrue if the specified data string can be converted to the specified data type; otherwise, false.
Use the CanConvert(String, ValidationDataType) method to determine whether the specified string can be converted to the specified data type. This method is commonly used to test whether a string can be converted to a compatible data type before performing an operation that depends on that data type.
This version of the method tests the value using the format used by the current culture. To test the value using a culture-neutral format, use the BaseCompareValidator.CanConvert(String, ValidationDataType, Boolean) overloaded version of this method.
The following example demonstrates using the CanConvert method to compare two integer values and determine whether the second integer can be converted.
<%@ Page Language="VB" AutoEventWireup="True" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server"> <title>BaseCompareValidator CanConvert Example</title> <script runat="server"> Sub Button_Click(sender As Object, e As EventArgs) ' Display whether the value of TextBox1 passes validation. If Page.IsValid Then lblOutput.Text = "Validation passed! " ' An input control passes validation if the value it is being ' compared to cannot be converted to the data type specified ' by the BaseCompareValidator.Type property. Be sure to use ' validation controls on each input control independently. ' Test the values being compared for their data types. ValidateType(Page.IsValid) Else lblOutput.Text = "Validation failed! " ' Test the values being compared for their data types. ValidateType(Page.IsValid) End If End Sub Sub ValidateType(Valid As Boolean) ' Display an error message if the value of TextBox1 cannot be ' converted to the data type specified by the ' BaseCompareValidator.Type property (in this case an integer). If Not BaseCompareValidator.CanConvert(TextBox1.Text, ValidationDataType.Integer) Then lblOutput.Text &= "The first value is not an integer. " End If ' Display an error message if the value of TextBox2 cannot be ' converted to the data type specified by the ' BaseCompareValidator.Type property (in this case an integer). If Not BaseCompareValidator.CanConvert(TextBox2.Text, ValidationDataType.Integer) Then ' An input control passes validation if the value it is being ' compared to cannot be converted to the data type specified ' by the BaseCompareValidator.Type property. ' Display a different message when this scenario occurs. If Valid Then lblOutput.Text &= "However, the second value is not an integer. " Else lblOutput.Text &= "The second value is not an integer. " End If End If End Sub </script> </head> <body> <form id="form1" runat="server"> <h3>BaseCompareValidator CanConvert Example</h3> <p> Enter an integer in each text box. <br /> Click "Validate" to compare the values <br /> for equality. </p> <table style="background-color:#eeeeee; padding:10"> <tr valign="top"> <td> <h5>Value 1:</h5> <asp:TextBox id="TextBox1" runat="server"/> </td> <td> <h5>Value 2:</h5> <asp:TextBox id="TextBox2" runat="server"/> <p> <asp:Button id="Button1" Text="Validate" OnClick="Button_Click" runat="server"/> </p> </td> </tr> </table> <asp:CompareValidator id="Compare1" ControlToValidate="TextBox1" ControlToCompare="TextBox2" EnableClientScript="False" Type="Integer" runat="server"/> <br /> <asp:Label id="lblOutput" Font-Names="verdana" Font-Size="10pt" runat="server"/> </form> </body> </html>
Available since 1.1