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Enum.TryParse(Of TEnum) Method (String, TEnum)

Converts the string representation of the name or numeric value of one or more enumerated constants to an equivalent enumerated object. The return value indicates whether the conversion succeeded.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

'Declaration
Public Shared Function TryParse(Of TEnum As Structure) ( _
	value As String, _
	<OutAttribute> ByRef result As TEnum _
) As Boolean

Type Parameters

TEnum

The enumeration type to which to convert value.

Parameters

value
Type: System.String

The string representation of the enumeration name or underlying value to convert.

result
Type: TEnum

When this method returns, result contains an object of type TEnum whose value is represented by value if the parse operation succeeds. If the parse operation fails, result contains the default value of the underlying type of TEnum. Note that this value need not be a member of the TEnum enumeration. This parameter is passed uninitialized.

Return Value

Type: System.Boolean
true if the value parameter was converted successfully; otherwise, false.

ExceptionCondition
ArgumentException

TEnum is not an enumeration type.

TryParse(Of TEnum)(String, TEnum) is identical to the Parse(Type, String) method, except that instead of throwing an exception, it returns false if the conversion fails. It eliminates the need for exception handling when parsing the string representation of an enumeration value.

The value parameter contains the string representation of an enumeration member's underlying value or named constant, or a list of named constants or underlying values delimited by commas (,). If value includes multiple named constants or values, one or more blank spaces can precede or follow each value, name, or comma in value. If value is a list, result reflects the value of the specified names or underlying values combined with a bitwise OR operation. If value is the string representation of the name of an enumeration value, the comparison of value with enumeration names is case-sensitive.

If value is a name that does not correspond to a named constant of TEnum, the method returns false. If value is the string representation of an integer that does not represent an underlying value of the TEnum enumeration, the method returns an enumeration member whose underlying value is value converted to an integral type. If this behavior is undesirable, call the IsDefined method to ensure that a particular string representation of an integer is actually a member of TEnum.

The following example defines a Colors enumeration, calls the TryParse(Of TEnum)(String, TEnum) method to convert strings to their corresponding enumeration values, and calls the IsDefined method to ensure that particular integral values are underlying values in the Colors enumeration.

<Flags> Enum Colors As Integer
   None = 0
   Red = 1
   Green = 2
   Blue = 4
End Enum 

Module Example
   Public Sub Main()
      Dim colorStrings() As String = {"0", "2", "8", "blue", "Blue", "Yellow", "Red, Green"}
      For Each colorString As String In colorStrings
         Dim colorValue As Colors
         If [Enum].TryParse(colorString, colorValue) Then         
            If [Enum].IsDefined(GetType(Colors), colorValue) Or colorValue.ToString().Contains(",") Then 
               Console.WriteLine("Converted '{0}' to {1}.", colorString, colorValue.ToString())
            Else
               Console.WriteLine("{0} is not an underlying value of the Colors enumeration.", colorString)            
            End If                     
         Else
            Console.WriteLine("{0} is not a member of the Colors enumeration.", colorString)
         End If 
      Next 
   End Sub 
End Module 
' The example displays the following output: 
'    Converted '0' to None. 
'    Converted '2' to Green. 
'    8 is not an underlying value of the Colors enumeration. 
'    blue is not a member of the Colors enumeration. 
'    Converted 'Blue' to Blue. 
'    Yellow is not a member of the Colors enumeration. 
'    Converted 'Red, Green' to Red, Green.

.NET Framework

Supported in: 4.5, 4

.NET Framework Client Profile

Supported in: 4

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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