C# 11 Character and String Data Types

Most software needs a way to store human-readable data in the form of characters and words. This chapter explores the use of string and character data types. The topic of building strings from multiple variables using a concept known as string interpolation is also covered.

Character data type

When talking about characters, we are referring to individual letters and numbers. For example, the letter ‘a’ is a character, as is the visual representation of the number ‘1’. Such characters may be stored in a C# char type. A char can contain one character and one character only. It is important to be aware that a character is not limited to those in the English alphabet. Characters are stored internally in C# as grapheme clusters. A grapheme cluster combines two or more Unicode scalars to represent a single visible character.

In addition, characters can be used for counting in loops and even in mathematical expressions. To assign a character to a variable or constant, surround the character with single quotes:

char myVar = 'a';
const char myConst = 'b';

The following lines assign a variety of different characters to char type variables:

char myChar1 = 'f';
char myChar2 = ':';
char myChar3 = 'X';

Characters may also be referenced using Unicode code points. The following example assigns a smiley face symbol (☺) to a variable using Unicode and then prints it:

char myChar4 = '\u263A';

System.Console.WriteLine(myChar4);

Output:

☺

Special characters

In addition to the standard set of characters outlined above, a range of special characters (also called escape sequences) is available for specifying items such as a new line, tab, or a specific Unicode value within a string. These special characters are identified by prefixing the character with a backslash (a concept referred to as escaping).

The escape sequence for a new line special character, for example, is \n. The following code fragment uses this new line special character to add blank lines within a string:

System.Console.WriteLine("This is a line of text.\n\n\nAn this is another.");

Output:

This is a line of text.


An this is another.Code language: JavaScript (javascript)

Any character preceded by a backslash is considered a special character and treated accordingly. This raises the question as to what to do if you actually want a backslash character. This is achieved by escaping the backslash itself (\\):

System.Console.WriteLine("C# special characters are escaped using the \\ character.);

Output:

C# special characters are escaped using the \ character.Code language: PHP (php)

Commonly used special characters supported by C# are as follows:

  • \n – Newline
  • \r – Carriage return
  • \t – Horizontal tab
  • \\ – Backslash
  • \” – Double quote (used when placing a double quote into a string declaration)
  • \’ – Single quote (used when placing a single quote into a string declaration)
  • \unn – Single-byte Unicode scalar where nn is replaced by two hexadecimal digits representing the Unicode character.
  • \unnnn – Double-byte Unicode scalar where nnnn is replaced by four hexadecimal digits representing the Unicode character.
  • \unnnnnnnn – Four-byte Unicode scalar where nnnnnnnn is replaced by eight hexadecimal digits representing the Unicode character.

String data type

Previously, we looked at storing individual characters in a char variable. While this works for storing a single letter, number, or Unicode scalar, it is of little use for storing entire words or sentences. For this purpose, the string variable type is supported by C#. Constants or variables of type string can store a string of any number of characters.

String literal values are surrounded by double quotes ("). For example:

string myString = "This is string is literal.";

Verbatim string literals

A regular string value will interpret special characters. The following code, for example, consists of a string containing multiple special characters:

string myString = "This is some text\n\n\tand this is some more.";

As shown above, the only way to make the text span multiple lines is to use the \n escape character when using a standard string literal. The following code, for example, will not compile:

string myString = "This is some text

    and this is some more.";

For a string literal to be interpreted precisely as written, it must be declared as a verbatim string literal type.

Verbatim string literals ignore the special meaning of escape characters and can span multiple lines. To declare a string literal as verbatim, prefix the declaration with the @ character. For example, this allows literals such as the following to be expressed:

string myString = @"Hi Team,

The file located at 'C:\Users\demo\newdata.txt'

uses the \t sequence to insert tabs into text. 

                Best regards

                        John";

System.Console.WriteLine(myString);

Output:

Hi Team,

The file located at 'C:\Users\demo\newdata.txt'

uses the \t sequence to insert tabs into text.

                Best regards

                        JohnCode language: JavaScript (javascript)

String interpolation

Strings may also be constructed using combinations of strings, variables, constants, expressions, and function calls using string interpolation.

This involves embedding items into a string by prefixing the literal declaration with $ character and wrapping the item as follows where {item} is a constant or variable name, a function call, or even an expression such as a mathematical calculation:

int count = 10;
string = $"The current count is {count}";

The following code, for example, creates a new string variable using string interpolation to embed content from a variety of sources before outputting it to the console:

string userName = "John";
int inboxCount = 25;
int maxCount = 100;

var message = $"{userName} has {inboxCount} messages. Message capacity remaining is {maxCount - inboxCount}.";

System.Console.WriteLine(message);

Output:

John has 25 messages. Message capacity remaining is 75.

If you need to wrap content in braces ({}) without it being interpreted as interpolated values, use double braces ({{}}) as follows:

string userName = "John";

var message = $"{userName} reported seeing error code 10 {{low battery}}.";

System.Console.WriteLine(message);

Output:

John reported seeing error code 10 {low battery}.

Interpolation may also be used within verbatim string literals by prefixing the string with either $@ or @$:

string userName = "John";
int inboxCount = 25;
int maxCount = 100;

var message = $@"{userName} has {inboxCount} messages. 

        Message capacity remaining is {maxCount - inboxCount}.";

System.Console.WriteLine(message);

Output:

John has 25 messages.

        Message capacity remaining is 75.

Note: Interpolated string literals can only be assigned to variables. An attempt to assign an interpolated string to a constant will result in a compiler error.

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