C# Cheat Sheet

A C# cheat sheet to act as a quick reference with syntax examples.

Data Types

Types

Type	Represents	Range	Default Value
bool	Boolean value	True or False	False
byte	8-bit unsigned integer	0 to 255	0
char	16-bit Unicode character	U +0000 to U +ffff	‘\0’
decimal	128-bit precise decimal values with 28-29 significant digits	(-7.9 x 1028 to 7.9 x 1028) / 100 to 28	0.0M
double	64-bit double-precision floating point type	(+/-)5.0 x 10-324 to (+/-)1.7 x 10308	0.0D
float	32-bit single-precision floating point type	-3.4 x 1038 to + 3.4 x 1038	0.0F
int	32-bit signed integer type	-2,147,483,648 to 2,147,483,647	0
long	64-bit signed integer type	-9,223,372,036,854,775,808 to 9,223,372,036,854,775,807	0L
sbyte	8-bit signed integer type	-128 to 127	0
short	16-bit signed integer type	-32,768 to 32,767	0
uint	32-bit unsigned integer type	0 to 4,294,967,295	0
ulong	64-bit unsigned integer type	0 to 18,446,744,073,709,551,615	0
ushort	16-bit unsigned integer type	0 to 65,535	0

Type Conversion

ToBoolean	Converts a type to a Boolean value, where possible.
ToByte	Converts a type to a byte.
ToChar	Converts a type to a single Unicode character, where possible.
ToDateTime	Converts a type (integer or string type) to date-time structures.
ToDecimal	Converts a floating-point or integer type to a decimal type.
ToDouble	Converts a type to a double type.
ToInt16	Converts a type to a 16-bit integer.
ToInt32	Converts a type to a 32-bit integer.
ToInt64	Converts a type to a 64-bit integer.
ToSbyte	Converts a type to a signed byte type.
ToSingle	Converts a type to a small floating-point number.
ToString	Converts a type to a string.
ToType	Converts a type to a specified type.
ToUInt16	Converts a type to an unsigned int type.
ToUInt32	Converts a type to an unsigned long type.
ToUInt64	Converts a type to an unsigned big integer.

Literal data types examples

//Literal data types:

	// char literal - requires single quotation operator.
	Console.WriteLine('b');

	// int literal - requires no additional operators.
	Console.WriteLine(123);
	
	// string literal - requires double quotation operators.
	Console.WriteLine("Hello!");

	// decimal literal - requires a literal suffix
	Console.WriteLine(12.3m);

	// boolean literal - requires a true or false value.
	Console.WriteLine(true);
	Console.WriteLine(false);

Variables

Variable types

Integral types	sbyte, byte, short, ushort, int, uint, long, ulong, and char
Floating point types	float and double
Decimal types	decimal
Boolean types	true or false values, as assigned
Nullable types	Nullable data types

Defining

<type> <name>;

Initialising

<name> = <value>;

Define and initialise

<type> <name> = <value>;

Example

// Define variable
string firstName;

// Initialise defined variable
firstName = "Bob";

// Define and initialise variable - best practice.
string firstName = "Bob";

// Implicitly typed local variable - It instructs the compiler to infer the type.
var message = "Hello world!";

String operations

Character escape sequence

\	\ character
'	‘ character
"	” character
\?	? character
\a	Alert or bell
\b	Backspace
\f	Form feed
\n	Newline
\r	Carriage return
\t	Horizontal tab
\v	Vertical tab
\xhh . . .	Hexadecimal number of one or more digits

Escape sequence examples

New line and tab

Console.WriteLine("Hello\nWorld!");

Console.WriteLine("Hello\tWorld!");

Output:

Hello
World!

Hello   World!

Double quotation

Console.WriteLine("Hello \"World\"!");

Output:

Hello "World"!

Backslashes

Console.WriteLine("c:\\source\\repos");

Output:

c:\source\repos

Example using newline, double quote and tab together

Console.WriteLine("Generating invoices for customer \"ABC Corp\" ...\n");
Console.WriteLine("Invoice: 1021\t\tComplete!");
Console.WriteLine("Invoice: 1022\t\tComplete!");
Console.WriteLine("\nOutput Directory:\t");

Output:

Generating invoices for customer "ABC Corp" ...

Invoice: 1021		Complete!
Invoice: 1022		Complete!

Output Directory:

Verbatim string literal

// use the @ directive before the literal string.
Console.WriteLine(@"   c:\source\repos   
      (this is where your code goes)");

Output:

c:\source\repos   
      (this is where your code goes)

Unicode escape characters

// You can add encoded characters in literal strings using the `\u` escape sequence, followed by a four-character Unicode (UFT-16).

// Kon'nichiwa World
Console.WriteLine("\u3053\u3093\u306B\u3061\u306F World!");

Output:

こんにちは World!

String Concatenation

To concatenate two strings together, you use the string concatenation operator, which is the plus + symbol.

string firstName = "Bob";
string message = "Hello " + firstName;
Console.WriteLine(message);

Output:

Hello Bob

Multiple concatenation operations in the same line of code.

string firstName = "Bob";
string greeting = "Hello";
Console.WriteLine(greeting + " " + firstName + "!");

Output:

Hello Bob!

String interpolation

Instead of writing this:

string message = greeting + " " + firstName + "!";

You can write this:

string message = $"{greeting} {firstName}!";

Combine 2 variables with string interpolation:

string firstName = "Bob";
string greeting = "Hello";
Console.WriteLine($"{greeting} {firstName}!");

Output:

Hello Bob!

Combine verbatim literals and string interpolation.

string projectName = "First-Project";
Console.WriteLine($@"C:\Output\{projectName}\Data");

Output:

C:\Output\First-Project\Data

Numeric Operations

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