diff options
Diffstat (limited to 'csharp.html.markdown')
| -rw-r--r-- | csharp.html.markdown | 123 |
1 files changed, 99 insertions, 24 deletions
diff --git a/csharp.html.markdown b/csharp.html.markdown index 47dd9683..479b7f01 100644 --- a/csharp.html.markdown +++ b/csharp.html.markdown @@ -5,6 +5,7 @@ contributors: - ["Max Yankov", "https://github.com/golergka"] - ["Melvyn Laïly", "http://x2a.yt"] - ["Shaun McCarthy", "http://www.shaunmccarthy.com"] + - ["Wouter Van Schandevijl", "http://github.com/laoujin"] filename: LearnCSharp.cs --- @@ -18,22 +19,29 @@ C# is an elegant and type-safe object-oriented language that enables developers Multi-line comments look like this */ /// <summary> -/// This is an XML documentation comment +/// This is an XML documentation comment which can be used to generate external +/// documentation or provide context help within an IDE /// </summary> +//public void MethodOrClassOrOtherWithParsableHelp() {} -// Specify namespaces application will be using +// Specify the namespaces this source code will be using +// The namespaces below are all part of the standard .NET Framework Class Libary using System; using System.Collections.Generic; -using System.Data.Entity; using System.Dynamic; using System.Linq; -using System.Linq.Expressions; using System.Net; using System.Threading.Tasks; using System.IO; -// defines scope to organize code into "packages" -namespace Learning +// But this one is not: +using System.Data.Entity; +// In order to be able to use it, you need to add a dll reference +// This can be done with the NuGet package manager: `Install-Package EntityFramework` + +// Namespaces define scope to organize code into "packages" or "modules" +// Using this code from another source file: using Learning.CSharp; +namespace Learning.CSharp { // Each .cs file should at least contain a class with the same name as the file // you're allowed to do otherwise, but shouldn't for sanity. @@ -125,7 +133,7 @@ on a new line! ""Wow!"", the masses cried"; // Use const or read-only to make a variable immutable // const values are calculated at compile time - const int HOURS_I_WORK_PER_WEEK = 9001; + const int HoursWorkPerWeek = 9001; /////////////////////////////////////////////////// // Data Structures @@ -242,8 +250,15 @@ on a new line! ""Wow!"", the masses cried"; int fooDoWhile = 0; do { - //Iterated 100 times, fooDoWhile 0->99 + // Start iteration 100 times, fooDoWhile 0->99 + if (false) + continue; // skip the current iteration + fooDoWhile++; + + if (fooDoWhile == 50) + break; // breaks from the loop completely + } while (fooDoWhile < 100); //for loop structure => for(<start_statement>; <conditional>; <step>) @@ -301,7 +316,7 @@ on a new line! ""Wow!"", the masses cried"; // Converting data // Convert String To Integer - // this will throw an Exception on failure + // this will throw a FormatException on failure int.Parse("123");//returns an integer version of "123" // try parse will default to type default on failure @@ -315,6 +330,11 @@ on a new line! ""Wow!"", the masses cried"; Convert.ToString(123); // or tryInt.ToString(); + + // Casting + // Cast decimal 15 to a int + // and then implicitly cast to long + long x = (int) 15M; } /////////////////////////////////////// @@ -367,8 +387,12 @@ on a new line! ""Wow!"", the masses cried"; } // Methods can have the same name, as long as the signature is unique - public static void MethodSignatures(string maxCount) + // A method that differs only in return type is not unique + public static void MethodSignatures( + ref int maxCount, // Pass by reference + out int count) { + count = 15; // out param must be assigned before control leaves the method } // GENERICS @@ -400,6 +424,10 @@ on a new line! ""Wow!"", the masses cried"; MethodSignatures(3, 1, 3, "Some", "Extra", "Strings"); MethodSignatures(3, another: 3); // explicity set a parameter, skipping optional ones + // BY REF AND OUT PARAMETERS + int maxCount = 0, count; // ref params must have value + MethodSignatures(ref maxCount, out count); + // EXTENSION METHODS int i = 3; i.Print(); // Defined below @@ -435,6 +463,31 @@ on a new line! ""Wow!"", the masses cried"; Func<int, int> square = (x) => x * x; // Last T item is the return value Console.WriteLine(square(3)); // 9 + // ERROR HANDLING - coping with an uncertain world + try + { + var funBike = PennyFarthing.CreateWithGears(6); + + // will no longer execute because CreateWithGears throws an exception + string some = ""; + if (true) some = null; + some.ToLower(); // throws a NullReferenceException + } + catch (NotSupportedException) + { + Console.WriteLine("Not so much fun now!"); + } + catch (Exception ex) // catch all other exceptions + { + throw new ApplicationException("It hit the fan", ex); + // throw; // A rethrow that preserves the callstack + } + // catch { } // catch-all without capturing the Exception + finally + { + // executes after try or catch + } + // DISPOSABLE RESOURCES MANAGEMENT - let you handle unmanaged resources easily. // Most of objects that access unmanaged resources (file handle, device contexts, etc.) // implement the IDisposable interface. The using statement takes care of @@ -595,10 +648,26 @@ on a new line! ""Wow!"", the masses cried"; public BikeBrand Brand; // After declaring an enum type, we can declare the field of this type + // Decorate an enum with the FlagsAttribute to indicate that multiple values can be switched on + [Flags] // Any class derived from Attribute can be used to decorate types, methods, parameters etc + public enum BikeAccessories + { + None = 0, + Bell = 1, + MudGuards = 2, // need to set the values manually! + Racks = 4, + Lights = 8, + FullPackage = Bell | MudGuards | Racks | Lights + } + + // Usage: aBike.Accessories.HasFlag(Bicycle.BikeAccessories.Bell) + // Before .NET 4: (aBike.Accessories & Bicycle.BikeAccessories.Bell) == Bicycle.BikeAccessories.Bell + public BikeAccessories Accessories { get; set; } + // Static members belong to the type itself rather then specific object. // You can access them without a reference to any object: // Console.WriteLine("Bicycles created: " + Bicycle.bicyclesCreated); - static public int BicyclesCreated = 0; + public static int BicyclesCreated { get; set; } // readonly values are set at run time // they can only be assigned upon declaration or in a constructor @@ -682,7 +751,7 @@ on a new line! ""Wow!"", the masses cried"; // All though this is not entirely useful in this example, you // could do bicycle[0] which yields "chris" to get the first passenger or // bicycle[1] = "lisa" to set the passenger. (of this apparent quattrocycle) - private string[] passengers = { "chris", "phil", "darren", "regina" } + private string[] passengers = { "chris", "phil", "darren", "regina" }; public string this[int i] { @@ -737,10 +806,17 @@ on a new line! ""Wow!"", the masses cried"; } set { - throw new ArgumentException("You can't change gears on a PennyFarthing"); + throw new InvalidOperationException("You can't change gears on a PennyFarthing"); } } + public static PennyFarthing CreateWithGears(int gears) + { + var penny = new PennyFarthing(1, 1); + penny.Gear = gears; // Oops, can't do this! + return penny; + } + public override string Info() { string result = "PennyFarthing bicycle "; @@ -784,7 +860,7 @@ on a new line! ""Wow!"", the masses cried"; /// EntityFramework Code First is awesome (similar to Ruby's ActiveRecord, but bidirectional) /// http://msdn.microsoft.com/en-us/data/jj193542.aspx /// </summary> - public class BikeRepository : DbSet + public class BikeRepository : DbContext { public BikeRepository() : base() @@ -798,13 +874,15 @@ on a new line! ""Wow!"", the masses cried"; ## Topics Not Covered - * Flags * Attributes - * Static properties - * Exceptions, Abstraction - * ASP.NET (Web Forms/MVC/WebMatrix) - * Winforms - * Windows Presentation Foundation (WPF) + * async/await, yield, pragma directives + * Web Development + * ASP.NET MVC & WebApi (new) + * ASP.NET Web Forms (old) + * WebMatrix (tool) + * Desktop Development + * Windows Presentation Foundation (WPF) (new) + * Winforms (old) ## Further Reading @@ -817,7 +895,4 @@ on a new line! ""Wow!"", the masses cried"; * [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# Coding Conventions](http://msdn.microsoft.com/en-us/library/vstudio/ff926074.aspx) |