' This example demonstrates overloads of the TryParse method for
' several base types, and the TryParseExact method for DateTime.
' In most cases, this example uses the most complex overload; that is, the overload
' with the most parameters for a particular type. If a complex overload specifies
' null (Nothing in Visual Basic) for the IFormatProvider parameter, formatting
' information is obtained from the culture associated with the current thread.
' If a complex overload specifies the style parameter, the parameter value is
' the default value used by the equivalent simple overload.
Imports System
Imports System.Globalization
Class Sample
Public Shared Sub Main()
Dim result As Boolean
Dim ci As CultureInfo
Dim nl As String = Environment.NewLine
Dim msg1 As String = _
"This example demonstrates overloads of the TryParse method for{0}" & _
"several base types, as well as the TryParseExact method for DateTime.{0}"
Dim msg2 As String = "Non-numeric types:{0}"
Dim msg3 As String = "{0}Numeric types:{0}"
Dim msg4 As String = "{0}The following types are not CLS-compliant:{0}"
' Non-numeric types.
Dim booleanVal As [Boolean]
Dim charVal As [Char]
Dim datetimeVal As DateTime
' Numeric types.
Dim byteVal As [Byte]
Dim int16Val As Int16
Dim int32Val As Int32
Dim int64Val As Int64
Dim decimalVal As [Decimal]
Dim singleVal As [Single]
Dim doubleVal As [Double]
' The following types are not CLS-compliant.
Dim sbyteVal As SByte
Dim uint16Val As UInt16
Dim uint32Val As UInt32
Dim uint64Val As UInt64
'
Console.WriteLine(msg1, nl)
' Non-numeric types:
Console.WriteLine(msg2, nl)
' DateTime
' TryParse:
' Assume current culture is en-US, and dates of the form: MMDDYYYY.
result = DateTime.TryParse("7/4/2004 12:34:56", datetimeVal)
Show(result, "DateTime #1", datetimeVal.ToString())
' Use fr-FR culture, and dates of the form: DDMMYYYY.
ci = New CultureInfo("fr-FR")
result = DateTime.TryParse("4/7/2004 12:34:56", ci, DateTimeStyles.None, datetimeVal)
Show(result, "DateTime #2", datetimeVal.ToString())
' TryParseExact:
' Use fr-FR culture. The format, "G", is short date and long time.
result = DateTime.TryParseExact("04/07/2004 12:34:56", "G", ci, DateTimeStyles.None, datetimeVal)
Show(result, "DateTime #3", datetimeVal.ToString())
' Assume en-US culture.
Dim dateFormats As String() = {"f", "F", "g", "G"}
result = DateTime.TryParseExact("7/4/2004 12:34:56 PM", dateFormats, Nothing, DateTimeStyles.None, datetimeVal)
Show(result, "DateTime #4", datetimeVal.ToString())
Console.WriteLine()
' Boolean
result = [Boolean].TryParse("true", booleanVal)
Show(result, "Boolean", booleanVal.ToString())
' Char
result = [Char].TryParse("A", charVal)
Show(result, "Char", charVal.ToString())
' Numeric types:
Console.WriteLine(msg3, nl)
' Byte
result = [Byte].TryParse("1", NumberStyles.Integer, Nothing, byteVal)
Show(result, "Byte", byteVal.ToString())
' Int16
result = Int16.TryParse("-2", NumberStyles.Integer, Nothing, int16Val)
Show(result, "Int16", int16Val.ToString())
' Int32
result = Int32.TryParse("3", NumberStyles.Integer, Nothing, int32Val)
Show(result, "Int32", int32Val.ToString())
' Int64
result = Int64.TryParse("4", NumberStyles.Integer, Nothing, int64Val)
Show(result, "Int64", int64Val.ToString())
' Decimal
result = [Decimal].TryParse("-5.5", NumberStyles.Number, Nothing, decimalVal)
Show(result, "Decimal", decimalVal.ToString())
' Single
result = [Single].TryParse("6.6", NumberStyles.Float Or NumberStyles.AllowThousands, Nothing, singleVal)
Show(result, "Single", singleVal.ToString())
' Double
result = [Double].TryParse("-7", NumberStyles.Float Or NumberStyles.AllowThousands, Nothing, doubleVal)
Show(result, "Double", doubleVal.ToString())
' Use the simple Double.TryParse overload, but specify an invalid value.
result = [Double].TryParse("abc", doubleVal)
Show(result, "Double #2", doubleVal.ToString())
'
Console.WriteLine(msg4, nl)
' SByte
result = SByte.TryParse("-8", NumberStyles.Integer, Nothing, sbyteVal)
Show(result, "SByte", sbyteVal.ToString())
' UInt16
result = UInt16.TryParse("9", NumberStyles.Integer, Nothing, uint16Val)
Show(result, "UInt16", uint16Val.ToString())
' UInt32
result = UInt32.TryParse("10", NumberStyles.Integer, Nothing, uint32Val)
Show(result, "UInt32", uint32Val.ToString())
' UInt64
result = UInt64.TryParse("11", NumberStyles.Integer, Nothing, uint64Val)
Show(result, "UInt64", uint64Val.ToString())
End Sub 'Main
Protected Shared Sub Show(parseResult As Boolean, typeName As String, parseValue As String)
Dim msgSuccess As String = "Parse for {0} = {1}"
Dim msgFailure As String = "** Parse for {0} failed. Invalid input."
'
If parseResult = True Then
Console.WriteLine(msgSuccess, typeName, parseValue)
Else
Console.WriteLine(msgFailure, typeName)
End If
End Sub 'Show
End Class 'Sample '
'This example produces the following results:
'
'This example demonstrates overloads of the TryParse method for
'several base types, as well as the TryParseExact method for DateTime.
'
'Non-numeric types:
'
'Parse for DateTime #1 = 7/4/2004 12:34:56 PM
'Parse for DateTime #2 = 7/4/2004 12:34:56 PM
'Parse for DateTime #3 = 7/4/2004 12:34:56 PM
'Parse for DateTime #4 = 7/4/2004 12:34:56 PM
'
'Parse for Boolean = True
'Parse for Char = A
'
'Numeric types:
'
'Parse for Byte = 1
'Parse for Int16 = -2
'Parse for Int32 = 3
'Parse for Int64 = 4
'Parse for Decimal = -5.5
'Parse for Single = 6.6
'Parse for Double = -7
'** Parse for Double #2 failed. Invalid input.
'
'The following types are not CLS-compliant:
'
'Parse for SByte = -8
'Parse for UInt16 = 9
'Parse for UInt32 = 10
'Parse for UInt64 = 11
'