String.IsInterned(String) Method method is used to retrieve a reference to a specified String. This method looks up the specified string in the intern pool.
If the specified string has already been interned, a reference to that instance is returned. Otherwise, null is returned. Here the intern pool is a table that contains a single instance of each unique literal string constant declared in a program, as well as any unique instance of String you add programmatically by calling the Intern method.
Note: The main difference between String.Intern(String) Method and String.IsInterned(String) Method is that Intern method returns a reference if the string doesn’t exist by adding a reference of the specified string to the intern pool. But the IsInterned method returns null if the string doesn’t exist.
public static string IsInterned (string strA);
Here, strA is a string which is used to search for in the intern pool.
Return Value: The return type of this method is System.String. This method will return a reference to strA if it is present in the CLR(Common Language Runtime) intern pool. Otherwise, return null.
Exception: This method will give ArgumentNullException of the str is null.
Below given are some examples to understand the implementation in a better way:
Tuesday: Yes Wednesday: Yes Thursday: Yes Monday-day: No
System.ArgumentNullException: Value cannot be null.
Parameter name: str