我有3个类似的功能,只根据数字类型改变：
<Extension()> _
Public Function ToNullableShort(ByVal str As String) As Short?
Dim intReturn As Short
If Short.TryParse(str,intReturn) Then
Return intReturn
Else
Return Nothing
End If
End Function
<Extension()> _
Public Function ToNullableByte(ByVal str As String) As Byte?
Dim intReturn As Byte
If Byte.TryParse(str,intReturn) Then
Return intReturn
Else
Return Nothing
End If
End Function
<Extension()> _
Public Function ToNullableLong(ByVal str As String) As Long?
Dim intReturn As Long
If Long.TryParse(str,intReturn) Then
Return intReturn
Else
Return Nothing
End If
End Function
这里有一个相同的问题(在C#中)：
Convert string to nullable type (int,double,etc…)
Public Function ConvertString(Of T As Structure)(ByVal value As String) As System.Nullable(Of T)
Try
Return DirectCast(Convert.ChangeType(value,GetType(T)),T)
Catch
Return Nothing
End Try
End Function