string is a reference type or value type

String is reference type not value type and it is stored on the heap whereas value type is stored on stack.
String is a reference type as it knows the size of the reference but not of the data and hence data size is not predefined.
Strings are immutable for the sake of memory management where they resemble the value types.
So String are reference type in all other aspects except being immutable and StringBuilder is the mutable reference type.

string is reference type but really special one. When you do operation of both string values like in your example
C = A, there is nothing in this operation simular to normal class behavior. So C doesn't have a reference of A. In that operation, a new string class is created and the value from string A is copied to string C. String C and String A are pointing in completly different memory address. That is way, when you have many string operation, for example loop and in every iteration you have a string manipulation, because of new string class generation, that operation is performance leak. In that situation it is preffered to use StringBuilder. Why, because StringBuilder doesn't create new string for any string operation.

Now for question, why string is not value type and it's reference type.
When you have let's say int value, Int type has defined lenght and that is 4 byte. And for every value type you know the exact memory space that will take. But for string you don't know that. It will be stupid to have a string type in wich you should always define how long it is. And if you want to put in that string variable a value with bigger lenght that string is defined, that will be disallowed.
Why is string a special class. It is special because you have a reference class, but the way of using it, looks like a value type. So, that's why you do operation like:
string C = A, and not string C = new string(A);
You don't have to instance string class because .NET framework do that for you when you first time set it's value. If you not set it's value string has value of null like any other reference type. Every language platform has a special treatment for string type. .NET is not exclusion from that too.

All objects in .Net are reference types.

string is a reference type.
It can't be a value-type, as value-types need a known size for the stack etc. As a reference-type, the size of the reference is known in advance, even if the size of the string isn't.

It behaves like you expect a value-type to behave because it is immutable; i.e. it doesn't change once created. But there are lots of other immutable reference-types. Delegate instances, for example.
*=except for inside StringBuilder, but you never see it while it is doing this.

for more details refer this:

http://www.yoda.arachsys.com/csharp/strings.html[^]

hope this helps :)

The type is a reference type thoroughly imitating value semantic.

You will understand the very special nature of the reference type System.String if you read about interning.

See the property System.String.IsInterned and the method System.String.Intern, http://msdn.microsoft.com/en-us/library/system.string.isinterned.aspx[^], http://msdn.microsoft.com/en-us/library/system.string.intern.aspx[^].

One important thing about having immutable string and interning is thread-safety.

—SA

sting are reference type.
object also reference type
integer is as value type

definitely string is a reference type in .net

In .Net Framework Strings are immutable reference types. All .net datatypes has default size except string and user type. So String is a Reference type, because its does not have default allocation size. The maximum string length will depend on your machine's architecture and memory allocation situation, but the String.Length property is a 32-bit integer, so there's an effective upper bound of Int32.MaxValue. More about......Is string a value type or a reference type

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