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Merge pull request #948 from Laoujin/master

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[CSharp/en]Some fixes and additions
This commit is contained in:
Levi Bostian 2015-02-01 12:24:36 -06:00
commit 705e40497d
1 changed files with 99 additions and 24 deletions
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@ -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)