String in C#

hi,

StringBuilder is more efficient in cases where there is a large amount of string manipulation. Strings are immutable, so each time a string is changed, a new instance in memory is created.
System.StringBuilder is mutable where variety of operations can be performed
System.String is immutable variable value may change But original data value will be discarded and new value will be in memory.

hope this will help u.

please read the below article.

http://www.c-sharpcorner.com/UploadFile/8832bd/string-vs-stringbuilder-in-net/

string is immutable means, if you create a string instance then you can't change it. If you do any operation on the string instance, it will create a new string instance. (ie) It will create a new memory space and allocate the new value there. It is an overhead.

Whereas stringbuilder is muttable. It is exactly opposite to string. Whenever you do any operation on stringbuilder, it will not create new instance.

If you wanted to do lot of string concatenation, its better to use stringbuilder rather than string.