Boolean.Parse Method
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Updated: October 2010
Converts the specified string representation of a logical value to its Boolean equivalent, or throws an exception if the string is not equivalent to the value of Boolean.TrueString or Boolean.FalseString.
Namespace: System
Assembly: mscorlib (in mscorlib.dll)
Syntax
'Declaration
Public Shared Function Parse ( _
value As String _
) As Boolean
public static bool Parse(
string value
)
Parameters
- value
Type: System.String
A string containing the value to convert.
Return Value
Type: System.Boolean
true if value is equivalent to the value of the TrueString field; false if value is equivalent to the value of the FalseString field.
Exceptions
| Exception | Condition |
|---|---|
| ArgumentNullException | value is nulla null reference (Nothing in Visual Basic). |
| FormatException | value is not equivalent to the value of the TrueString or FalseString field. |
Remarks
The value parameter, optionally preceded or trailed by white space, must contain a string that is equivalent to the value of either the TrueString or FalseString field; otherwise, a FormatException is thrown. The comparison is case-insensitive.
Examples
The following example calls the Parse method to parse an array of strings. Note that the parse operation succeeds only if the string to be parsed is "True" (the value of the TrueString field) or "False" (the value of the FalseString field) in a case-insensitive comparison.
Module Example
Public Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
Dim values() As String = { Nothing, String.Empty, "True", "False",
"true", "false", " true ", "0",
"1", "-1", "string" }
For Each value In values
Try
Dim flag As Boolean = Boolean.Parse(value)
outputBlock.Text += String.Format("'{0}' --> {1}", value, flag) & vbCrLf
Catch e As ArgumentException
outputBlock.Text &= "Cannot parse a null string." & vbCrLf
Catch e As FormatException
outputBlock.Text += String.Format("Cannot parse '{0}'.", value) & vbCrLf
End Try
Next
End Sub
End Module
' The example displays the following output:
' Cannot parse a null string.
' Cannot parse ''.
' 'True' --> True
' 'False' --> False
' 'true' --> True
' 'false' --> False
' ' true ' --> True
' Cannot parse '0'.
' Cannot parse '1'.
' Cannot parse '-1'.
' Cannot parse 'string'.
using System;
public class Example
{
public static void Demo(System.Windows.Controls.TextBlock outputBlock)
{
string[] values = { null, String.Empty, "True", "False",
"true", "false", " true ", "0",
"1", "-1", "string" };
foreach (var value in values)
{
try
{
bool flag = Boolean.Parse(value);
outputBlock.Text += String.Format("'{0}' --> {1}", value, flag) + "\n";
}
catch (ArgumentException)
{
outputBlock.Text += "Cannot parse a null string." + "\n";
}
catch (FormatException)
{
outputBlock.Text += String.Format("Cannot parse '{0}'.", value) + "\n";
}
}
}
}
// The example displays the following output:
// Cannot parse a null string.
// Cannot parse ''.
// 'True' --> True
// 'False' --> False
// 'true' --> True
// 'false' --> False
// ' true ' --> True
// Cannot parse '0'.
// Cannot parse '1'.
// Cannot parse '-1'.
// Cannot parse 'string'.
Version Information
Silverlight
Supported in: 5, 4, 3
Silverlight for Windows Phone
Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0
XNA Framework
Supported in: Xbox 360, Windows Phone OS 7.0
Platforms
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.
See Also
Reference
Other Resources
Change History
Date |
History |
Reason |
|---|---|---|
October 2010 |
Revised extensively and replaced the example. |
Customer feedback. |
June 2010 |
Corrected return value information. |
Customer feedback. |