BaseCompareValidator.CanConvert Method
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Determines whether the specified string can be converted to the specified data type.
| CanConvert(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. |
| CanConvert(String, ValidationDataType, Boolean) |
Determines whether the specified string can be converted to the specified data type. This version of the overloaded method allows you to specify whether values are tested using a culture-neutral format. |
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.
public:
static bool CanConvert(System::String ^ text, System::Web::UI::WebControls::ValidationDataType type);public static bool CanConvert(string text, System.Web.UI.WebControls.ValidationDataType type);static member CanConvert : string * System.Web.UI.WebControls.ValidationDataType -> boolPublic Shared Function CanConvert (text As String, type As ValidationDataType) As BooleanParameters
- text
- String
The string to test.
- type
- ValidationDataType
One of the ValidationDataType values.
Returns
true if the specified data string can be converted to the specified data type; otherwise, false.
Examples
The following example demonstrates using the CanConvert method to compare two integer values and determine whether the second integer can be converted.
<%@ Page Language="C#" 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">
void Button_Click(Object sender, EventArgs e)
{
// Display whether the value of TextBox1 passes validation.
if (Page.IsValid)
{
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);
}
}
void ValidateType(bool Valid)
{
// 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 (!BaseCompareValidator.CanConvert(TextBox1.Text, ValidationDataType.Integer))
{
lblOutput.Text += "The first value is not an integer. ";
}
// 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 (!BaseCompareValidator.CanConvert(TextBox2.Text, ValidationDataType.Integer))
{
// 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)
{
lblOutput.Text += "However, the second value is not an integer. ";
}
else
{
lblOutput.Text += "The second value is not an integer. ";
}
}
}
</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>
<%@ 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>
Remarks
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.
See also
Applies to
.NET Framework 4.8.1 and other versions
| Product | Versions |
|---|---|
| .NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
Determines whether the specified string can be converted to the specified data type. This version of the overloaded method allows you to specify whether values are tested using a culture-neutral format.
public:
static bool CanConvert(System::String ^ text, System::Web::UI::WebControls::ValidationDataType type, bool cultureInvariant);public static bool CanConvert(string text, System.Web.UI.WebControls.ValidationDataType type, bool cultureInvariant);static member CanConvert : string * System.Web.UI.WebControls.ValidationDataType * bool -> boolPublic Shared Function CanConvert (text As String, type As ValidationDataType, cultureInvariant As Boolean) As BooleanParameters
- text
- String
The string to test.
- type
- ValidationDataType
One of the ValidationDataType enumeration values.
- cultureInvariant
- Boolean
true to test values using a culture-neutral format; otherwise, false.
Returns
true if the specified data string can be converted to the specified data type; otherwise, false.
Remarks
Use the CanConvert(String, ValidationDataType, Boolean) 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. To indicate that values should be tested using a culture-neutral format, pass in true for the cultureInvariant parameter; otherwise, values are tested using the format used by the current culture. When testing a value using the format used by the current culture, consider using the BaseCompareValidator.CanConvert(String, ValidationDataType) overloaded version of this method.
See also
Applies to
.NET Framework 4.8.1 and other versions
| Product | Versions |
|---|---|
| .NET Framework | 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
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