C# | String
In C#, string is a sequence of Unicode characters or array of characters. The range of Unicode characters will be U+0000 to U+FFFF. The array of characters is also termed as the text. So the string is the representation of the text. A string is an important concept and sometimes people get confused whether the string is a keyword or an object or a class. So let’s clear out this concept.
A string is represented by class System.String. The “string” keyword is an alias for System.String class and instead of writing System.String one can use String which is a shorthand for System.String class. So we can say string and String both can be used as an alias of System.String class. So string is an object of System.String class.
string s1 = “GeeksforGeeks”; // creating the string using string keyword
String s2 = “GFG”; // creating the string using String class
System.String s3 = “Pro Geek”; // creating the string using String class
The String class is defined in the .NET base class library. In other words a String object is a sequential collection of System.Char objects which represents a string. The maximum size of String object in memory is 2GB or about 1 billion characters. System.String class is immutable, i.e once created its state cannot be altered.
Program: To illustrate how to declare the string and initialize the string. Also, below program show the declaration and initialization of a string in a single line.
Name: Geek Id: 33 Marks: 97 Rank: 1
- It is a reference type.
- It’s immutable( its state cannot be altered).
- It can contain nulls.
- It overloads the operator(==).
Differences between String and System.String :
The string is an alias for System.String. Both String and System.String means same and it will not affect the performance of the application. “string” is keyword in C#. So the main difference comes in the context, how to use these:
- The String is used for the declaration but System.String is used for accessing static string methods.
- The String is used to declare fields, properties etc. that it will use the predefined type System.String. It is the easy way to use.
- The String has to use the System.String class methods, such as String.SubString, String.IndexOf etc. The string is only an alias of System.String.
Note: In .NET, the text is stored as a sequential collection of the Char objects so there is no null-terminating character at the end of a C# string. Therefore a C# string can contain any number of embedded null characters (‘\0’).
String arrays: We can also create the array of string and assigns values to it. The string arrays can be created as follows:
String  array_variable = new String[Length_of_array]
- Example: To illustrate the creation of string arrays and assigning values to it
value at Index position 0 is Geeks value at Index position 1 is For value at Index position 2 is Geeks
Reading String from User-Input: A string can be read out from the user input. ReadLine() method of console class is used to read a string from user input.
Hello Geeks !
Enter the String User Entered: Hello Geeks !
Different Ways for Creating a String:
- Create a string from a literal
- Create a string using concatenation
- Create a string using a constructor
- Create a string using a property or a method
- Create a string using formatting
Create a string from a literal: It is the most common way to create a string. In this, a user has to define string variable and then assign the value within the double quotes. We can use any type of characters within double quotes except some special character like a backslash (\).
- Program: To illustrate the string creation using literals
Create a string using concatenation: We can create a string by using string concatenation operator “+” in C#. To create a single string from any combination of String instances and string literals, the string concatenation operator (+) is used to combine or merge one or more string.
- Program: To illustrates the use of the string concatenation operator
Create a string using Constructor: The String class has been several overloaded constructors which take an array of characters or bytes. Some of the constructors include pointers to character arrays or signed byte arrays as parameters.
- Program: To illustrates Creation of a string using the constructor
Create a string using a Property or a Method: To retrieving a property or calling a method which always returns a string. For example, using methods of the String class to extract a substring from a larger string.
- Program: To illustrate the Creation of a string using a Property or a Method
Create a string using Format: The “Format” method is used to convert the value or object to its string representation. The String.Format method returns a string.
- Program: To illustrate the creation of string using Format method
10 BMW Cars color are Red
String Class Properties: The String class has two properties as follows:
- Chars: It is used to get the Char object at a specified position in the current String object.
- Length: It is used to get the number of characters in the current String object. To know more about the string class properties please go to String Properties in C#.