C#

# Getting Started

Hello.cs

class Hello {
    // main method
    static void Main(string[] args)
    {
        // Output: Hello, world!
        Console.WriteLine("Hello, world!");
    }
}

Variables

int intNum = 9;
long longNum = 9999999;
float floatNum = 9.99F;
double doubleNum = 99.999;
decimal decimalNum = 99.9999M;
char letter = 'D';
bool @bool = true;
string site = "quickref.me";

var num = 999;
var str = "999";
var bo = false;

Primitive Data Types

Data Type Size Range
int 4 bytes -231 to 231-1
long 8 bytes -263 to 263-1
float 4 bytes 6 to 7 decimal digits
double 8 bytes 15 decimal digits
decimal 16 bytes 28 to 29 decimal digits
char 2 bytes 0 to 65535
bool 1 bit true / false
string 2 bytes per char N/A

Comments

// Single-line comment

/* Multi-line 
   comment */

// TODO: Adds comment to a task list in Visual Studio

/// Single-line comment used for documentation

/** Multi-line comment 
    used for documentation **/

Strings

string first = "John";
string last = "Doe";

// string concatenation
string name = first + " " + last;
Console.WriteLine(name); // => John Doe

User Input

Console.WriteLine("Enter number:");
if(int.TryParse(Console.ReadLine(),out int input))
{
                // Input validated
  Console.WriteLine($"You entered {input}");
}

Conditionals

int j = 10;

if (j == 10) {
  Console.WriteLine("I get printed");
} else if (j > 10) {
  Console.WriteLine("I don't");
} else {
  Console.WriteLine("I also don't");
}

Arrays

char[] chars = new char[10];
chars[0] = 'a';
chars[1] = 'b';

string[] letters = {"A", "B", "C"};
int[] mylist = {100, 200};
bool[] answers = {true, false};

Loops

int[] numbers = {1, 2, 3, 4, 5};

for(int i = 0; i < numbers.Length; i++) {
  Console.WriteLine(numbers[i]);
}

foreach(int num in numbers) {
  Console.WriteLine(num);
}

# C# Strings

String concatenation

string first = "John";
string last = "Doe";

string name = first + " " + last;
Console.WriteLine(name); // => John Doe

String interpolation

string first = "John";
string last = "Doe";

string name = $"{first} {last}";
Console.WriteLine(name); // => John Doe

Verbatim strings

string longString = @"I can type any characters in here !#@$%^&*()__+ '' \n \t except double quotes and I will be taken literally. I even work with multiple lines.";

Member Example

// Using property of System.String
string lengthOfString = "How long?";
lengthOfString.Length           // => 9

// Using methods of System.String
lengthOfString.Contains("How"); // => true

String Members

Member Description
Length A property that returns the length of the string.
Compare() A static method that compares two strings.
Contains() Determines if the string contains a specific substring.
Equals() Determines if the two strings have the same character data.
Format() Formats a string via the {0} notation and by using other primitives.
Trim() Removes all instances of specific characters from trailing and leading characters. Defaults to removing leading and trailing spaces.
Split() Removes the provided character and creates an array out of the remaining characters on either side.
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