Why strings are immutable in net

In such cases, specifying all 4 hex digits e. At compile time, verbatim strings are converted to ordinary strings with all the same escape sequences. Therefore, if you view a verbatim string in the debugger watch window, you will see the escape characters that were added by the compiler, not the verbatim version from your source code.

A format string is a string whose contents are determined dynamically at run time. Format strings are created by embedding interpolated expressions or placeholders inside of braces within a string. There are two methods to create format strings: string interpolation and composite formatting.

Available in C 6. If you are new to string interpolation, see the String interpolation - C interactive tutorial for a quick overview. Use string interpolation to improve the readability and maintainability of your code. String interpolation achieves the same results as the String. Format method, but improves ease of use and inline clarity.

Beginning with C 10, you can use string interpolation to initialize a constant string when all the expressions used for placeholders are also constant strings. The String. Format utilizes placeholders in braces to create a format string. This example results in similar output to the string interpolation method used above. For more information on formatting. NET types see Formatting Types in. A substring is any sequence of characters that is contained in a string.

Use the Substring method to create a new string from a part of the original string. You can search for one or more occurrences of a substring by using the IndexOf method. Use the Replace method to replace all occurrences of a specified substring with a new string. Like the Substring method, Replace actually returns a new string and does not modify the original string.

For more information, see How to search strings and How to modify string contents. You can use array notation with an index value to acquire read-only access to individual characters, as in the following example:. If the String methods do not provide the functionality that you must have to modify individual characters in a string, you can use a StringBuilder object to modify the individual chars "in-place", and then create a new string to store the results by using the StringBuilder methods.

In the following example, assume that you must modify the original string in a particular way and then store the results for future use:. An empty string is an instance of a System. String object that contains zero characters. Empty strings are used often in various programming scenarios to represent a blank text field.

You can call methods on empty strings because they are valid System. String objects. Empty strings are initialized as follows:. By contrast, a null string does not refer to an instance of a System. String object and any attempt to call a method on a null string causes a NullReferenceException.

However, you can use null strings in concatenation and comparison operations with other strings. What are fail-safe and fail-fast Iterators in Java What are method references?

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What is a stacktrace? What are different ways to create a string object in Java? Why do designers of. NET just like the creators of Java decided to implement immutable text strings? For optimization reasons mainly because of comparison speed , texts can be stored in a special table intern pool maintained by the CLR.

The idea is to avoid creating a number of variables defining the same string. If the strings were modifiable, change to the value of variable a , would also change the value of b and d.

Immutability of strings has positive significance in multithreaded applications — any text amendment causes creation of a new variable so there is no need to set up the lock to avoid conflicts while multiple threads simultaneously access text.

Another important reason for immutability is the widespread use of strings as keys in hash tables. Would calculation of position of the element in table make any sense if it would be possible to modify the value of a key? The following listing shows that the "change" to variable used as the key does not affect the operation of the hash table:. What would happen in the case of modifiable strings can be seen through a block of code that uses unsafe mode to actually change the string used as key:.

Immutability is also related to the fact that the string is stored internally as an array - the data structure representing a continuous address space which for performance reasons does not support insert operation. Sign in Email. Forgot your password? Search within: Articles Quick Answers Messages.

Technical Blog. View Original. Tagged as C. Stats Why strings are immutable and what are the implications of it? Please Sign up or sign in to vote. Ever wondered why it is better to create new string then alter one?