String.IsNullOrEmpty Method

Parameters

• value
  Type: System.String
  The string to test.

Return Value

Type: System.Boolean
true if the value parameter is nulla null reference (Nothing in Visual Basic) or an empty string (""); otherwise, false.

result = s Is Nothing OrElse s = String.Empty

result = s == null || s == String.Empty;

Class Example
   Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
      Dim s1 As String = "abcd"
      Dim s2 As String = ""
      Dim s3 As String = Nothing

      outputBlock.Text += String.Format("String s1 {0}.", Test(s1)) & vbCrLf
      outputBlock.Text += String.Format("String s2 {0}.", Test(s2)) & vbCrLf
      outputBlock.Text += String.Format("String s3 {0}.", Test(s3)) & vbCrLf
   End Sub

   Public Shared Function Test(ByVal s As String) As String
      If String.IsNullOrEmpty(s) Then
         Return "is null or empty"
      Else
         Return String.Format("(""{0}"") is not null or empty", s)
      End If
   End Function 
End Class
' The example displays the following output:
'       String s1 ("abcd") is not null or empty.
'       String s2 is null or empty.
'       String s3 is null or empty.

using System;

class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      string s1 = "abcd";
      string s2 = "";
      string s3 = null;

      outputBlock.Text += String.Format("String s1 {0}.", Test(s1)) + "\n";
      outputBlock.Text += String.Format("String s2 {0}.", Test(s2)) + "\n";
      outputBlock.Text += String.Format("String s3 {0}.", Test(s3)) + "\n";
   }

   public static String Test(string s)
   {
      if (String.IsNullOrEmpty(s))
         return "is null or empty";
      else
         return String.Format("(\"{0}\") is not null or empty", s);
   }
}
// The example displays the following output:
//       String s1 ("abcd") is not null or empty.
//       String s2 is null or empty.
//       String s3 is null or empty.