diff options
Diffstat (limited to 'csharp.html.markdown')
| -rw-r--r-- | csharp.html.markdown | 261 |
1 files changed, 214 insertions, 47 deletions
diff --git a/csharp.html.markdown b/csharp.html.markdown index c98a7da9..37573e01 100644 --- a/csharp.html.markdown +++ b/csharp.html.markdown @@ -14,20 +14,22 @@ filename: LearnCSharp.cs C# is an elegant and type-safe object-oriented language that enables developers to build a variety of secure and robust applications that run on the .NET Framework. -[Read more here.](http://msdn.microsoft.com/en-us/library/vstudio/z1zx9t92.aspx) +[Read more here.](https://docs.microsoft.com/dotnet/csharp/getting-started/introduction-to-the-csharp-language-and-the-net-framework) ```c# // Single-line comments start with // + /* Multi-line comments look like this */ + /// <summary> /// This is an XML documentation comment which can be used to generate external /// documentation or provide context help within an IDE /// </summary> /// <param name="firstParam">This is some parameter documentation for firstParam</param> /// <returns>Information on the returned value of a function</returns> -//public void MethodOrClassOrOtherWithParsableHelp(string firstParam) {} +public void MethodOrClassOrOtherWithParsableHelp(string firstParam) {} // Specify the namespaces this source code will be using // The namespaces below are all part of the standard .NET Framework Class Library @@ -254,7 +256,7 @@ on a new line! ""Wow!"", the masses cried"; int fooWhile = 0; while (fooWhile < 100) { - //Iterated 100 times, fooWhile 0->99 + // Iterated 100 times, fooWhile 0->99 fooWhile++; } @@ -273,10 +275,10 @@ on a new line! ""Wow!"", the masses cried"; } while (fooDoWhile < 100); - //for loop structure => for(<start_statement>; <conditional>; <step>) + // for loop structure => for(<start_statement>; <conditional>; <step>) for (int fooFor = 0; fooFor < 10; fooFor++) { - //Iterated 10 times, fooFor 0->9 + // Iterated 10 times, fooFor 0->9 } // For Each Loop @@ -287,7 +289,7 @@ on a new line! ""Wow!"", the masses cried"; // (The ToCharArray() could be removed, because a string also implements IEnumerable) foreach (char character in "Hello World".ToCharArray()) { - //Iterated over all the characters in the string + // Iterated over all the characters in the string } // Switch Case @@ -329,7 +331,7 @@ on a new line! ""Wow!"", the masses cried"; // Convert String To Integer // this will throw a FormatException on failure - int.Parse("123");//returns an integer version of "123" + int.Parse("123"); // returns an integer version of "123" // try parse will default to type default on failure // in this case: 0 @@ -344,7 +346,7 @@ on a new line! ""Wow!"", the masses cried"; tryInt.ToString(); // Casting - // Cast decimal 15 to a int + // Cast decimal 15 to an int // and then implicitly cast to long long x = (int) 15M; } @@ -373,7 +375,7 @@ on a new line! ""Wow!"", the masses cried"; Console.Read(); } // End main method - // CONSOLE ENTRY A console application must have a main method as an entry point + // CONSOLE ENTRY - A console application must have a main method as an entry point public static void Main(string[] args) { OtherInterestingFeatures(); @@ -404,7 +406,7 @@ on a new line! ""Wow!"", the masses cried"; ref int maxCount, // Pass by reference out int count) { - //the argument passed in as 'count' will hold the value of 15 outside of this function + // the argument passed in as 'count' will hold the value of 15 outside of this function count = 15; // out param must be assigned before control leaves the method } @@ -552,7 +554,7 @@ on a new line! ""Wow!"", the masses cried"; } // PARALLEL FRAMEWORK - // http://blogs.msdn.com/b/csharpfaq/archive/2010/06/01/parallel-programming-in-net-framework-4-getting-started.aspx + // https://devblogs.microsoft.com/csharpfaq/parallel-programming-in-net-framework-4-getting-started/ var words = new List<string> {"dog", "cat", "horse", "pony"}; @@ -564,11 +566,11 @@ on a new line! ""Wow!"", the masses cried"; } ); - //Running this will produce different outputs - //since each thread finishes at different times. - //Some example outputs are: - //cat dog horse pony - //dog horse pony cat + // Running this will produce different outputs + // since each thread finishes at different times. + // Some example outputs are: + // cat dog horse pony + // dog horse pony cat // DYNAMIC OBJECTS (great for working with other languages) dynamic student = new ExpandoObject(); @@ -640,6 +642,54 @@ 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. @@ -817,7 +867,7 @@ on a new line! ""Wow!"", the masses cried"; } } - //Method to display the attribute values of this Object. + // Method to display the attribute values of this Object. public virtual string Info() { return "Gear: " + Gear + @@ -912,7 +962,7 @@ on a new line! ""Wow!"", the masses cried"; /// <summary> /// Used to connect to DB for LinqToSql example. /// EntityFramework Code First is awesome (similar to Ruby's ActiveRecord, but bidirectional) - /// http://msdn.microsoft.com/en-us/data/jj193542.aspx + /// https://docs.microsoft.com/ef/ef6/modeling/code-first/workflows/new-database /// </summary> public class BikeRepository : DbContext { @@ -1021,7 +1071,7 @@ on a new line! ""Wow!"", the masses cried"; { private static bool LogException(Exception ex) { - /* log exception somewhere */ + // log exception somewhere return false; } @@ -1069,12 +1119,12 @@ on a new line! ""Wow!"", the masses cried"; [Obsolete("Use NewMethod instead", false)] public static void ObsoleteMethod() { - /* obsolete code */ + // obsolete code } public static void NewMethod() { - /* new code */ + // new code } public static void Main() @@ -1106,25 +1156,144 @@ 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 + } + } } ``` @@ -1143,13 +1312,11 @@ namespace Csharp7 ## Further Reading - * [DotNetPerls](http://www.dotnetperls.com) - * [C# in Depth](http://manning.com/skeet2) - * [Programming C#](http://shop.oreilly.com/product/0636920024064.do) - * [LINQ](http://shop.oreilly.com/product/9780596519254.do) - * [MSDN Library](http://msdn.microsoft.com/en-us/library/618ayhy6.aspx) - * [ASP.NET MVC Tutorials](http://www.asp.net/mvc/tutorials) - * [ASP.NET Web Matrix Tutorials](http://www.asp.net/web-pages/tutorials) - * [ASP.NET Web Forms Tutorials](http://www.asp.net/web-forms/tutorials) - * [Windows Forms Programming in C#](http://www.amazon.com/Windows-Forms-Programming-Chris-Sells/dp/0321116208) - * [C# Coding Conventions](http://msdn.microsoft.com/en-us/library/vstudio/ff926074.aspx) + * [C# language reference](https://docs.microsoft.com/dotnet/csharp/language-reference/) + * [Learn .NET](https://dotnet.microsoft.com/learn) + * [C# Coding Conventions](https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/inside-a-program/coding-conventions) + * [DotNetPerls](https://www.dotnetperls.com/) + * [C# in Depth](https://manning.com/skeet3) + * [Programming C# 5.0](http://shop.oreilly.com/product/0636920024064) + * [LINQ Pocket Reference](http://shop.oreilly.com/product/9780596519254) + * [Windows Forms Programming in C#](https://www.amazon.com/Windows-Forms-Programming-Chris-Sells/dp/0321116208) |