string-Intern

      [System.Security.SecuritySafeCritical]  // auto-generated
        public static String Intern(String str) {
            if (str==null) {
                throw new ArgumentNullException("str");
            }
            Contract.Ensures(Contract.Result<String>().Length == str.Length);
            Contract.Ensures(str.Equals(Contract.Result<String>()));
            Contract.EndContractBlock();
 
            return Thread.GetDomain().GetOrInternString(str);
        }

案例

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 == '{0}'", s1);
    Console.WriteLine("s2 == '{0}'", s2);
    Console.WriteLine("s3 == '{0}'", s3);
    Console.WriteLine("Is s2 the same reference as s1?: {0}", (Object)s2==(Object)s1); 
    Console.WriteLine("Is s3 the same reference as s1?: {0}", (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
*/