Boolean.Parse Method

[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]

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

Public Shared Function Parse ( _
    value As String _
) As Boolean
public static bool Parse(
    string value
)

Parameters

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 nullNothingnullptra 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

Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Platforms

Windows Phone

See Also

Reference

Boolean Structure

System Namespace

TrueString

FalseString