Getting Started

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);
}

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};

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");
}

User Input

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

Strings

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

See: Strings

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 \*\*/

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

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;

Hello.cs

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

Compiling and running (make sure you are in the project directory)

$ dotnet run
Hello, world!

Comments