String.Intern(String) Method

Definition

Namespace:

System

Assembly:

System.Runtime.dll

Source:

String.CoreCLR.cs

Retrieves the system's reference to the specified String.

public:
 static System::String ^ Intern(System::String ^ str);

public static string Intern (string str);

static member Intern : string -> string

Public Shared Function Intern (str As String) As String

Parameters

str

String

A string to search for in the intern pool.

Returns

String

The system's reference to str, if it is interned; otherwise, a new reference to a string with the value of str.

Exceptions

ArgumentNullException

str is null.

Examples

The following example uses three strings that are equal in value to determine whether a newly created string and an interned string are equal.

// Sample for String::Intern(String)
using namespace System;
using namespace System::Text;
int main()
{
   String^ s1 = "MyTest";
   String^ s2 = (gcnew StringBuilder)->Append( "My" )->Append( "Test" )->ToString();
   String^ s3 = String::Intern( s2 );
   Console::WriteLine( "s1 == '{0}'", s1 );
   Console::WriteLine( "s2 == '{0}'", s2 );
   Console::WriteLine( "s3 == '{0}'", s3 );
   Console::WriteLine( "Is s2 the same reference as s1?: {0}", s2 == s1 );
   Console::WriteLine( "Is s3 the same reference as s1?: {0}", s3 == s1 );
}

/*
This example produces the following results:
s1 == 'MyTest'
s2 == 'MyTest'
s3 == 'MyTest'
Is s2 the same reference as s1?: False
Is s3 the same reference as s1?: True
*/

// Sample for String.Intern(String)
using System;
using System.Text;

class Sample
{
    public static void Main()
    {
        string s1 = "MyTest";
        string s2 = new StringBuilder().Append("My").Append("Test").ToString();
        string s3 = String.Intern(s2);
        Console.WriteLine($"s1 == {s1}");
        Console.WriteLine($"s2 == {s2}");
        Console.WriteLine($"s3 == {s3}");
        Console.WriteLine($"Is s2 the same reference as s1?: {(Object)s2 == (Object)s1}");
        Console.WriteLine($"Is s3 the same reference as s1?: {(Object)s3 == (Object)s1}");
    }
}
/*
This example produces the following results:
s1 == MyTest
s2 == MyTest
s3 == MyTest
Is s2 the same reference as s1?: False
Is s3 the same reference as s1?: True
*/

// Sample for String.Intern(String)
open System
open System.Text

let s1 = "MyTest"
let s2 = StringBuilder().Append("My").Append("Test").ToString()
let s3 = String.Intern s2
printfn $"s1 = {s1}"
printfn $"s2 = {s2}"
printfn $"s3 = {s3}"
printfn $"Is s2 the same reference as s1?: {s2 :> obj = s1 :> obj}"
printfn $"Is s3 the same reference as s1?: {s3 :> obj = s1 :> obj}"
(*
This example produces the following results:
s1 = MyTest
s2 = MyTest
s3 = MyTest
Is s2 the same reference as s1?: False
Is s3 the same reference as s1?: True
*)

Imports System.Text

Class Sample

    Public Shared Sub Main()
        Dim s1 As String = "MyTest"
        Dim s2 As String = New StringBuilder().Append("My").Append("Test").ToString()
        Dim s3 As String = String.Intern(s2)
        Console.WriteLine($"s1 = {s1}")
        Console.WriteLine($"s2 = {s2}")
        Console.WriteLine($"s3 = {s3}")
        Console.WriteLine($"Is s2 the same reference as s1?: {s2 Is s1}")
        Console.WriteLine($"Is s3 the same reference as s1?: {s3 Is s1}")
    End Sub
End Class
'
's1 = MyTest
's2 = MyTest
's3 = MyTest
'Is s2 the same reference as s1?: False
'Is s3 the same reference as s1?: True
'

Remarks

For more information about this API, see Supplemental API remarks for String.Intern.

See also

• IsInterned(String)