What is StringInterning?

[.NetIndia]

 

What is StringInterning?

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[Shivprasad Koirala]

Its the property of a SAX driver to get XML string with out method
calls
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[BabuLives]

Hai groups...

CLR maintain a table called Intern Pool for string storage.Intern pool
contain single instant of each distinct literal string constant.
For example if you have

string strEx1="DotNet";
string strEx2="DotNet";

The .NET compiler search for "DotNet" in intern pool,if it doesn't find

an entry ,it will create a string in heap and reference to the heap is
value of the string.For second string ,compiler check for the entry,it
finds one,so it will not create an entry this time,instead it returns
the value.

So MessageBox.Show(Object.ReferenceEquals (strEx1,strEx2).ToString());
returns True

Now consider following code:

string strEx1="DotNet";
string strEx2="Dot"+"Net";
MessageBox.Show(Object.ReferenceEquals (strEx1,strEx2).ToString());
returns False

When you create string dynamically ,string will not be added into
intern pool

Now string strEx3= string.Intern(strEx2) Intern method ,search intern
pool for the value of string strEx2 (ie,"DotNet") .it finds an entry,so

the method returns the same reference that is assigned to strEx1.

so MessageBox.Show(Object.ReferenceEquals (strEx1,strEx3).ToString());
returns True

There is another methods called IsInterned to checks whether the value
in interned or not.if it is not interned it returns a null
reference,else not null

Regards,
Satheesh babu