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String.IsNullOrEmpty Method

.NET Framework 4

Updated: December 2010

Indicates whether the specified string is null or an Empty string.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)
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public static bool IsNullOrEmpty(
	string value
)

Parameters

value
Type: System.String
The string to test.

Return Value

Type: System.Boolean
true if the value parameter is null or an empty string (""); otherwise, false.

IsNullOrEmpty is a convenience method that enables you to simultaneously test whether a String is null or its value is Empty. It is equivalent to the following code:

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

The following example determines whether each of three strings has a value, is an empty string or is null.

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using System;

class Sample 
{
    public static void Main() 
    {
    string s1 = "abcd";
    string s2 = "";
    string s3 = null;

    Console.WriteLine("String s1 {0}.", Test(s1));
    Console.WriteLine("String s2 {0}.", Test(s2));
    Console.WriteLine("String s3 {0}.", Test(s3));
    }

    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.

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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

Date

History

Reason

December 2010

Expanded the Remarks section and modified the example.

Customer feedback.
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Community Content Add
Annotations FAQ
Passing DBNULL to Function
This will throw an excetion as it DBNULL is not correct to be passed to a function that excepts strings? $0A better function would be one that accepts any type of implicitly and returns a String
<summary> ''' A NotNull function that will return a empty string if nothing or dbnull is passed, or return its original String Value '''
</summary>
<param name="Value">Object to be evaluated</param>
<returns>String</returns>
<remarks></remarks>;

Public Shared Function NN(Of T)(Value As T) As String
If Value Is Nothing OrElse IsDBNull(Value) Then
Return String.Empty
Else
Return Value.ToString()
End If
End Function
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