| title | description | ms.date | dev_langs | |||
|---|---|---|---|---|---|---|
System.String.IsNullOrEmpty method |
Learn about the System.String.IsNullOrEmpty method. |
01/24/2024 |
|
[!INCLUDE context]
xref:System.String.IsNullOrEmpty%2A is a convenience method that enables you to simultaneously test whether a xref:System.String is null or its value is xref:System.String.Empty?displayProperty=nameWithType. It is equivalent to the following code:
:::code language="csharp" source="./snippets/System/String/IsNullOrEmpty/csharp/isnullorempty1.cs" interactive="try-dotnet-method" id="Snippet1"::: :::code language="vb" source="./snippets/System/String/IsNullOrEmpty/vb/isnullorempty1.vb" id="Snippet1"::: :::code language="fsharp" source="./snippets/System/String/IsNullOrEmpty/fsharp/isnullorempty1.fs" id="Snippet1":::
You can use the xref:System.String.IsNullOrWhiteSpace%2A method to test whether a string is null, its value is xref:System.String.Empty?displayProperty=nameWithType, or it consists only of white-space characters.
A string is null if it has not been assigned a value (in C++ and Visual Basic) or if it has explicitly been assigned a value of null. Although the composite formatting feature can gracefully handle a null string, as the following example shows, attempting to call one if its members throws a xref:System.NullReferenceException.
:::code language="csharp" source="./snippets/System/String/IsNullOrEmpty/csharp/NullString1.cs" interactive="try-dotnet-method" id="Snippet2"::: :::code language="vb" source="./snippets/System/String/IsNullOrEmpty/vb/NullString1.vb" id="Snippet2"::: :::code language="fsharp" source="./snippets/System/String/IsNullOrEmpty/fsharp/NullString1.fs" id="Snippet2":::
A string is empty if it is explicitly assigned an empty string ("") or xref:System.String.Empty?displayProperty=nameWithType. An empty string has a xref:System.String.Length%2A of 0. The following example creates an empty string and displays its value and its length.
:::code language="csharp" source="./snippets/System/String/IsNullOrEmpty/csharp/NullString1.cs" interactive="try-dotnet-method" id="Snippet3"::: :::code language="vb" source="./snippets/System/String/IsNullOrEmpty/vb/NullString1.vb" id="Snippet3"::: :::code language="fsharp" source="./snippets/System/String/IsNullOrEmpty/fsharp/NullString2.fs" id="Snippet3":::