summaryrefslogtreecommitdiffhomepage
path: root/csharp.html.markdown
diff options
context:
space:
mode:
Diffstat (limited to 'csharp.html.markdown')
-rw-r--r--csharp.html.markdown209
1 files changed, 193 insertions, 16 deletions
diff --git a/csharp.html.markdown b/csharp.html.markdown
index 963f38f4..f27adf18 100644
--- a/csharp.html.markdown
+++ b/csharp.html.markdown
@@ -132,6 +132,12 @@ namespace Learning.CSharp
DateTime fooDate = DateTime.Now;
Console.WriteLine(fooDate.ToString("hh:mm, dd MMM yyyy"));
+ // Verbatim String
+ // You can use the @ symbol before a string literal to escape all characters in the string
+ string path = "C:\\Users\\User\\Desktop";
+ string verbatimPath = @"C:\Users\User\Desktop";
+ Console.WriteLine(path == verbatimPath); // => true
+
// You can split a string over two lines with the @ symbol. To escape " use ""
string bazString = @"Here's some stuff
on a new line! ""Wow!"", the masses cried";
@@ -634,6 +640,54 @@ on a new line! ""Wow!"", the masses cried";
}
}
+
+ // DELEGATES AND EVENTS
+ public class DelegateTest
+ {
+ public static int count = 0;
+ public static int Increment()
+ {
+ // increment count then return it
+ return ++count;
+ }
+
+ // A delegate is a reference to a method
+ // To reference the Increment method,
+ // first declare a delegate with the same signature
+ // ie. takes no arguments and returns an int
+ public delegate int IncrementDelegate();
+
+ // An event can also be used to trigger delegates
+ // Create an event with the delegate type
+ public static event IncrementDelegate MyEvent;
+
+ static void Main(string[] args)
+ {
+ // Refer to the Increment method by instantiating the delegate
+ // and passing the method itself in as an argument
+ IncrementDelegate inc = new IncrementDelegate(Increment);
+ Console.WriteLine(inc()); // => 1
+
+ // Delegates can be composed with the + operator
+ IncrementDelegate composedInc = inc;
+ composedInc += inc;
+ composedInc += inc;
+
+ // composedInc will run Increment 3 times
+ Console.WriteLine(composedInc()); // => 4
+
+
+ // Subscribe to the event with the delegate
+ MyEvent += new IncrementDelegate(Increment);
+ MyEvent += new IncrementDelegate(Increment);
+
+ // Trigger the event
+ // ie. run all delegates subscribed to this event
+ Console.WriteLine(MyEvent()); // => 6
+ }
+ }
+
+
// Class Declaration Syntax:
// <public/private/protected/internal> class <class name>{
// //data fields, constructors, functions all inside.
@@ -949,6 +1003,7 @@ on a new line! ""Wow!"", the masses cried";
// String interpolation by prefixing the string with $
// and wrapping the expression you want to interpolate with { braces }
+ // You can also combine both interpolated and verbatim strings with $@
public class Rectangle
{
public int Length { get; set; }
@@ -961,6 +1016,9 @@ on a new line! ""Wow!"", the masses cried";
{
Rectangle rect = new Rectangle { Length = 5, Width = 3 };
Console.WriteLine($"The length is {rect.Length} and the width is {rect.Width}");
+
+ string username = "User";
+ Console.WriteLine($@"C:\Users\{username}\Desktop");
}
}
@@ -1096,25 +1154,144 @@ namespace Learning.More.CSharp
}
}
+//New C# 7 Feature
+//Install Microsoft.Net.Compilers Latest from Nuget
+//Install System.ValueTuple Latest from Nuget
using System;
namespace Csharp7
{
- //New C# 7 Feature
- //Install Microsoft.Net.Compilers Latest from Nuget
- //Install System.ValueTuple Latest from Nuget
- class Program
- {
- static void Main(string[] args)
- {
- //Type 1 Declaration
- (string FirstName, string LastName) names1 = ("Peter", "Parker");
- Console.WriteLine(names1.FirstName);
-
- //Type 2 Declaration
- var names2 = (First:"Peter", Last:"Parker");
- Console.WriteLine(names2.Last);
- }
- }
+ // TUPLES, DECONSTRUCTION AND DISCARDS
+ class TuplesTest
+ {
+ public (string, string) GetName()
+ {
+ // Fields in tuples are by default named Item1, Item2...
+ var names1 = ("Peter", "Parker");
+ Console.WriteLine(names1.Item2); // => Parker
+
+ // Fields can instead be explicitly named
+ // Type 1 Declaration
+ (string FirstName, string LastName) names2 = ("Peter", "Parker");
+
+ // Type 2 Declaration
+ var names3 = (First:"Peter", Last:"Parker");
+
+ Console.WriteLine(names2.FirstName); // => Peter
+ Console.WriteLine(names3.Last); // => Parker
+
+ return names3;
+ }
+
+ public string GetLastName() {
+ var fullName = GetName();
+
+ // Tuples can be deconstructed
+ (string firstName, string lastName) = fullName;
+
+ // Fields in a deconstructed tuple can be discarded by using _
+ var (_, last) = fullName;
+ return last;
+ }
+
+ // Any type can be deconstructed in the same way by
+ // specifying a Deconstruct method
+ public int randomNumber = 4;
+ public int anotherRandomNumber = 10;
+
+ public void Deconstruct(out int randomNumber, out int anotherRandomNumber)
+ {
+ randomNumber = this.randomNumber;
+ anotherRandomNumber = this.anotherRandomNumber;
+ }
+
+ static void Main(string[] args)
+ {
+ var tt = new TuplesTest();
+ (int num1, int num2) = tt;
+ Console.WriteLine($"num1: {num1}, num2: {num2}"); // => num1: 4, num2: 10
+
+ Console.WriteLine(tt.GetLastName());
+ }
+ }
+
+ // PATTERN MATCHING
+ class PatternMatchingTest
+ {
+ public static (string, int)? CreateLogMessage(object data)
+ {
+ switch(data)
+ {
+ // Additional filtering using when
+ case System.Net.Http.HttpRequestException h when h.Message.Contains("404"):
+ return (h.Message, 404);
+ case System.Net.Http.HttpRequestException h when h.Message.Contains("400"):
+ return (h.Message, 400);
+ case Exception e:
+ return (e.Message, 500);
+ case string s:
+ return (s, s.Contains("Error") ? 500 : 200);
+ case null:
+ return null;
+ default:
+ return (data.ToString(), 500);
+ }
+ }
+ }
+
+ // REFERENCE LOCALS
+ // Allow you to return a reference to an object instead of just its value
+ class RefLocalsTest
+ {
+ // note ref in return
+ public static ref string FindItem(string[] arr, string el)
+ {
+ for(int i=0; i<arr.Length; i++)
+ {
+ if(arr[i] == el) {
+ // return the reference
+ return ref arr[i];
+ }
+ }
+ throw new Exception("Item not found");
+ }
+
+ public static void SomeMethod()
+ {
+ string[] arr = {"this", "is", "an", "array"};
+
+ // note refs everywhere
+ ref string item = ref FindItem(arr, "array");
+ item = "apple";
+ Console.WriteLine(arr[3]); // => apple
+ }
+ }
+
+ // LOCAL FUNCTIONS
+ class LocalFunctionTest
+ {
+ private static int _id = 0;
+ public int id;
+ public LocalFunctionTest()
+ {
+ id = generateId();
+
+ // This local function can only be accessed in this scope
+ int generateId()
+ {
+ return _id++;
+ }
+ }
+
+ public static void AnotherMethod()
+ {
+ var lf1 = new LocalFunctionTest();
+ var lf2 = new LocalFunctionTest();
+ Console.WriteLine($"{lf1.id}, {lf2.id}"); // => 0, 1
+
+ int id = generateId();
+ // error CS0103: The name 'generateId' does not exist in the current context
+ }
+ }
}
```