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. |