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Data Types

Value Types

Boolean Type

The boolean data type is used for representing logical values in programming. In most programming languages, including C#, it is commonly denoted as bool. The bool type can have only two possible values: true or false.

C#
bool isDone = true;

Use cases for the boolean type include:

  • Conditional Statements: Boolean values are frequently used in conditional statements (e.g., if, else, switch) to determine the flow of execution based on whether a condition is true or false.
  • Loop Control: Boolean expressions are often used to control the flow of loops (e.g., while, for, do-while). The loop continues as long as the boolean condition remains true.
  • Method Returns: Methods can return boolean values to indicate the success or failure of an operation.
  • Flagging State: Boolean variables are commonly used as flags to represent the state of a system or a specific feature.
  • Logical Operations: Boolean values can be combined using logical operators such as && (AND), || (OR), and ! (NOT) to form more complex conditions.

Character type

In C#, the char type represents a single 16-bit Unicode character. It is used to store individual characters, such as letters, digits, punctuation marks, and special symbols. The char type is part of the integral data types in C#, and it is commonly used to work with single characters in strings or to represent individual characters in various contexts.

C#
decimal choice = 'A';

Char literals are single characters enclosed in single quotes. Examples:

C#
char letterA = 'A';
char digit7 = '7';
char newline = '\n';

Escape Sequences

In C#, escape sequences are special sequences of characters that represent certain non-printable or special characters within a string. Escape sequences are used to include characters in strings that are difficult to represent directly. They are identified by a backslash \ followed by a specific character or combination of characters.

Here are some common escape sequences in C#:

Newline (\n)

Represents a newline character. When encountered in a string, it starts a new line.

C#
string multiLineString = "This is line 1.\nThis is line 2.";

Carriage Return (\r)

Represents a carriage return character. It is often used in combination with newline to represent a newline on different systems.

C#
string carriageReturnString = "Hello\rWorld";

Tab (\t)

Represents a horizontal tab character. It is used to create horizontal space in the text.

C#
string tabbedString = "Name:\tJohn";

Backspace (\b)

Represents a backspace character. It moves the cursor one position to the left.

C#
string backspaceString = "Backspace\bExample";

Single Quote (\')

Represents a single quote character.

C#
string singleQuoteString = "It\'s raining.";

Double Quote (\")

Represents a double quote character.

C#
string doubleQuoteString = "She said, \"Hello!\"";

Int Type

In C#, the int type is used to represent 32-bit signed integers. It is one of the integral data types in C# and is commonly used to store whole numbers without decimal points. The int type has a range of values from -2,147,483,648 to 2,147,483,647.

C#
int age = 25;

Float Type

In C#, the float type is used to represent single-precision floating-point numbers. It is one of the numeric data types in C# and is commonly used for representing real numbers that require decimal points. The float type provides a compromise between precision and memory usage, as it uses less memory compared to the double type but has a smaller range and less precision.

C#
double gradePointAverage = 3.14f;

Double Type

In C#, the double type is used to represent double-precision floating-point numbers. It is part of the numeric data types in C# and provides a higher precision compared to the float type. The double type is commonly used for representing real numbers that require decimal points and a larger range of values.

C#
double gradePointAverage = 3.14;

Decimal Type

C# also includes a floating-point type used for currency values. It is more accurate than using the double type.

C#
decimal paymentAmount = 34.23m;

Note

A floating-point literal (Ex. 34.23) is considered a double type. A float literal is expressed by succeeding the literal value with an 'F' (Ex. 34.23F) and a decimal literal with an 'M' (Ex. 34.23M).

Reference Types

Object Type

object is a data type that is the base for all other data types. It is an alias for the System.Object class in the Common Type System (CTS).

C#
object widget;

Future Lesson

The object type will be explained more in future modules.

String Type

The string type, which is the alias to the System.String .NET type in the Common Type System (CTS), represents a series of characters.

C#
string firstName = "Chris";`

Tip

It is best practice to be familiar with the members of the string type for any programming language you are developing with.

To understand what you can do with strings in C#, check out the String Class Documentation.

Type Conversions

Type conversion refers to the process of converting a value from one data type to another. Type conversion is necessary when you want to perform operations or assignments involving different data types. There are two main types of type conversion: implicit conversion and explicit conversion.

Implicit Conversion (Widening Conversion)

Implicit conversion, also known as widening conversion, is performed by the compiler automatically when there is no risk of losing data. It occurs when a smaller data type is converted to a larger data type.

C#
int intValue = 42;

// Implicit conversion from int to double
double doubleValue = intValue;

In the example above, the int value is implicitly converted to a double value, as there is no loss of precision.

Explicit Conversion (Narrowing Conversion)

Explicit conversion, also known as narrowing conversion, requires a cast operator and is performed when there is a risk of losing data. The programmer explicitly indicates the conversion using a cast.

C#
double doubleValue = 3.14;

// Explicit conversion from double to int
int intValue = (int)doubleValue;

In this example, the double value is explicitly converted to an int value. Note that information might be lost in this conversion, as decimals are truncated.

Common Conversion Methods

Casting

The cast operator (type) is used for explicit conversion.

C#
double doubleValue = 3.14;
int intValue = (int)doubleValue;

Convert Class

The Convert class provides methods for converting between types.

C#
int intValue = Convert.ToInt32(3.14);

ToString Method

The ToString method is used to convert a value to its string representation.

C#
int intValue = 42;
string stringValue = intValue.ToString();

Parse Methods

Parsing methods are used to convert strings to other types.

C#
string numberString = "42";
int intValue = int.Parse(numberString);

ToString and Parse in Enumerations

Enumerations can be converted to strings and parsed from strings.

C#
enum Color { Red, Green, Blue }
string colorString = Color.Red.ToString();
Color parsedColor = (Color)Enum.Parse(typeof(Color), "Green");

It's essential to be cautious with explicit conversions, especially when there's a risk of losing data. It's recommended to use conversion methods that handle potential errors gracefully, such as TryParse for parsing and Convert methods for basic conversions.

Other Useful Types

DateTime

The DateTime type represents dates and times with values ranging from January 1, 0001, 00:00:00 (midnight) to 11:59:59 PM, December 31, 9999 12. It is used to represent an instant of time.

Note

DateTime is a struct, not a class. You can think of a struct like a class, but it is a value type.

You can create a new instance of DateTime using one of its constructors. For example, you can create a new instance of the DateTime that represents the current date and time using the following code:

C#
DateTime now = DateTime.Now;

The DateTime struct provides a variety of methods that allow you to manipulate dates and times. For example, you can use the AddDays method to add a specified number of days to a date, or the ToString method to convert a date to a string representation.

Future Lesson

The DateTime type will be used in a future module.

Further Reading