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897 lines
34 KiB
C#
897 lines
34 KiB
C#
---
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language: c#
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filename: csharp-pt.cs
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contributors:
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- ["Robson Alves", "http://robsonalves.net/"]
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lang: pt-br
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---
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C# é uma linguagem elegante e altamente tipado orientada a objetos que permite aos desenvolvedores criarem uma variedade de aplicações seguras e robustas que são executadas no .NET Framework.
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[Read more here.](http://msdn.microsoft.com/pt-br/library/vstudio/z1zx9t92.aspx)
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```c#
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// Comentário de linha única começa com //
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/*
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Múltipas linhas é desta forma
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*/
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/// <summary>
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/// Esta é uma documentação comentário XML que pode ser usado para gerar externo
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/// documentação ou fornecer ajuda de contexto dentro de um IDE
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/// </summary>
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//public void MethodOrClassOrOtherWithParsableHelp() {}
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// Especificar qual namespace seu código irá usar
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// Os namespaces a seguir são padrões do .NET Framework Class Library
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using System;
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using System.Collections.Generic;
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using System.Dynamic;
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using System.Linq;
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using System.Net;
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using System.Threading.Tasks;
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using System.IO;
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// Mas este aqui não é :
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using System.Data.Entity;
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// Para que consiga utiliza-lo, você precisa adicionar novas referências
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// Isso pode ser feito com o gerenciador de pacotes NuGet : `Install-Package EntityFramework`
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// Namespaces são escopos definidos para organizar o códgo em "pacotes" or "módulos"
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// Usando este código a partir de outra arquivo de origem: using Learning.CSharp;
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namespace Learning.CSharp
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{
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// Cada .cs deve conter uma classe com o mesmo nome do arquivo
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// você está autorizado a contrariar isto, mas evite por sua sanidade.
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public class AprenderCsharp
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{
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// Sintaxe Básica - Pule para as CARACTERÍSTICAS INTERESSANTES se você ja usou Java ou C++ antes.
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public static void Syntax()
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{
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// Use Console.WriteLine para apresentar uma linha
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Console.WriteLine("Hello World");
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Console.WriteLine(
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"Integer: " + 10 +
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" Double: " + 3.14 +
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" Boolean: " + true);
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// Para apresentar sem incluir uma nova linha, use Console.Write
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Console.Write("Hello ");
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Console.Write("World");
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///////////////////////////////////////////////////
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// Tpos e Variáveis
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//
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// Declare uma variável usando <tipo> <nome>
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///////////////////////////////////////////////////
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// Sbyte - Signed 8-bit integer
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// (-128 <= sbyte <= 127)
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sbyte fooSbyte = 100;
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// Byte - Unsigned 8-bit integer
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// (0 <= byte <= 255)
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byte fooByte = 100;
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// Short - 16-bit integer
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// Signed - (-32,768 <= short <= 32,767)
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// Unsigned - (0 <= ushort <= 65,535)
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short fooShort = 10000;
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ushort fooUshort = 10000;
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// Integer - 32-bit integer
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int fooInt = 1; // (-2,147,483,648 <= int <= 2,147,483,647)
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uint fooUint = 1; // (0 <= uint <= 4,294,967,295)
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// Long - 64-bit integer
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long fooLong = 100000L; // (-9,223,372,036,854,775,808 <= long <= 9,223,372,036,854,775,807)
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ulong fooUlong = 100000L; // (0 <= ulong <= 18,446,744,073,709,551,615)
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// Numbers default to being int or uint depending on size.
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// L is used to denote that this variable value is of type long or ulong
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// Double - Double-precision 64-bit IEEE 754 Floating Point
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double fooDouble = 123.4; // Precision: 15-16 digits
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// Float - Single-precision 32-bit IEEE 754 Floating Point
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float fooFloat = 234.5f; // Precision: 7 digits
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// f is used to denote that this variable value is of type float
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// Decimal - a 128-bits data type, with more precision than other floating-point types,
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// suited for financial and monetary calculations
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decimal fooDecimal = 150.3m;
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// Boolean - true & false
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bool fooBoolean = true; // or false
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// Char - A single 16-bit Unicode character
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char fooChar = 'A';
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// Strings - ao contrário dos anteriores tipos base, que são todos os tipos de valor,
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// Uma string é um tipo de referência. Ou seja, você pode configurá-lo como nulo
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string fooString = "\"escape\" quotes and add \n (new lines) and \t (tabs)";
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Console.WriteLine(fooString);
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// Você pode acessar todos os caracteres de string com um indexador:
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char charFromString = fooString[1]; // => 'e'
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// Strings são imutáveis: você não pode fazer fooString[1] = 'X';
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// Compare strings com sua atual cultura, ignorando maiúsculas e minúsculas
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string.Compare(fooString, "x", StringComparison.CurrentCultureIgnoreCase);
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// Formatando, baseado no sprintf
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string fooFs = string.Format("Check Check, {0} {1}, {0} {1:0.0}", 1, 2);
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// Datas e formatações
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DateTime fooDate = DateTime.Now;
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Console.WriteLine(fooDate.ToString("hh:mm, dd MMM yyyy"));
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// Você pode juntar um string em mais de duas linhas com o símbolo @. Para escapar do " use ""
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string bazString = @"Here's some stuff
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on a new line! ""Wow!"", the masses cried";
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// Use const ou read-only para fazer uma variável imutável
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// os valores da const são calculados durante o tempo de compilação
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const int HoursWorkPerWeek = 9001;
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///////////////////////////////////////////////////
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// Estrutura de Dados
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///////////////////////////////////////////////////
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// Matrizes - zero indexado
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// O tamanho do array pode ser decidido ainda na declaração
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// O formato para declarar uma matriz é o seguinte:
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// <tipodado>[] <var nome> = new <tipodado>[<array tamanho>];
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int[] intArray = new int[10];
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// Outra forma de declarar & inicializar uma matriz
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int[] y = { 9000, 1000, 1337 };
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// Indexando uma matriz - Acessando um elemento
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Console.WriteLine("intArray @ 0: " + intArray[0]);
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// Matriz são alteráveis
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intArray[1] = 1;
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// Listas
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// Listas são usadas frequentemente tanto quanto matriz por serem mais flexiveis
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// O formato de declarar uma lista é o seguinte:
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// List<tipodado> <var nome> = new List<tipodado>();
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List<int> intList = new List<int>();
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List<string> stringList = new List<string>();
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List<int> z = new List<int> { 9000, 1000, 1337 }; // inicializar
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// O <> são para genéricos - Confira está interessante seção do material
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// Lista não possuem valores padrão.
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// Um valor deve ser adicionado antes e depois acessado pelo indexador
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intList.Add(1);
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Console.WriteLine("intList @ 0: " + intList[0]);
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// Outras estruturas de dados para conferir:
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// Pilha/Fila
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// Dicionário (uma implementação de map de hash)
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// HashSet
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// Read-only Coleção
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// Tuple (.Net 4+)
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///////////////////////////////////////
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// Operadores
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///////////////////////////////////////
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Console.WriteLine("\n->Operators");
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int i1 = 1, i2 = 2; // Forma curta para declarar diversas variáveis
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// Aritmética é clara
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Console.WriteLine(i1 + i2 - i1 * 3 / 7); // => 3
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// Modulo
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Console.WriteLine("11%3 = " + (11 % 3)); // => 2
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// Comparações de operadores
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Console.WriteLine("3 == 2? " + (3 == 2)); // => falso
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Console.WriteLine("3 != 2? " + (3 != 2)); // => verdadeiro
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Console.WriteLine("3 > 2? " + (3 > 2)); // => verdadeiro
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Console.WriteLine("3 < 2? " + (3 < 2)); // => falso
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Console.WriteLine("2 <= 2? " + (2 <= 2)); // => verdadeiro
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Console.WriteLine("2 >= 2? " + (2 >= 2)); // => verdadeiro
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// Operadores bit a bit (bitwise)
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/*
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~ Unário bitwise complemento
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<< Signed left shift
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>> Signed right shift
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& Bitwise AND
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^ Bitwise exclusivo OR
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| Bitwise inclusivo OR
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*/
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// Incrementações
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int i = 0;
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Console.WriteLine("\n->Inc/Dec-rementation");
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Console.WriteLine(i++); //i = 1. Post-Incrementation
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Console.WriteLine(++i); //i = 2. Pre-Incrementation
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Console.WriteLine(i--); //i = 1. Post-Decrementation
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Console.WriteLine(--i); //i = 0. Pre-Decrementation
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///////////////////////////////////////
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// Estrutura de Controle
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///////////////////////////////////////
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Console.WriteLine("\n->Control Structures");
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// Declaração if é como a linguagem C
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int j = 10;
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if (j == 10)
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{
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Console.WriteLine("I get printed");
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}
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else if (j > 10)
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{
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Console.WriteLine("I don't");
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}
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else
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{
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Console.WriteLine("I also don't");
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}
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// Operador Ternário
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// Um simples if/else pode ser escrito da seguinte forma
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// <condição> ? <verdadeiro> : <falso>
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int toCompare = 17;
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string isTrue = toCompare == 17 ? "True" : "False";
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// While loop
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int fooWhile = 0;
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while (fooWhile < 100)
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{
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//Iterated 100 times, fooWhile 0->99
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fooWhile++;
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}
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// Do While Loop
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int fooDoWhile = 0;
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do
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{
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// Inicia a interação 100 vezes, fooDoWhile 0->99
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if (false)
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continue; // pule a intereção atual para apróxima
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fooDoWhile++;
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if (fooDoWhile == 50)
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break; // Interrompe o laço inteiro
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} while (fooDoWhile < 100);
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//estrutura de loop for => for(<declaração para começar>; <condicional>; <passos>)
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for (int fooFor = 0; fooFor < 10; fooFor++)
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{
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//Iterado 10 vezes, fooFor 0->9
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}
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// For Each Loop
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// Estrutura do foreach => foreach(<Tipo Iterador> <Nome do Iterador> in <enumerable>)
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// O laço foreach percorre sobre qualquer objeto que implementa IEnumerable ou IEnumerable<T>
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// Toda a coleção de tipos (Array, List, Dictionary...) no .Net framework
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// implementa uma ou mais destas interfaces.
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// (O ToCharArray() pode ser removido, por que uma string também implementa IEnumerable)
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foreach (char character in "Hello World".ToCharArray())
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{
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//Iterated over all the characters in the string
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}
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// Switch Case
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// Um switch funciona com os tipos de dados byte, short, char, e int.
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// Isto também funcional com tipos enumeradors (discutidos em Tipos Enum),
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// A classe String, and a few special classes that wrap
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// tipos primitívos: Character, Byte, Short, and Integer.
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int month = 3;
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string monthString;
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switch (month)
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{
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case 1:
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monthString = "January";
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break;
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case 2:
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monthString = "February";
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break;
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case 3:
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monthString = "March";
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break;
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// You can assign more than one case to an action
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// But you can't add an action without a break before another case
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// (if you want to do this, you would have to explicitly add a goto case x
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case 6:
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case 7:
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case 8:
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monthString = "Summer time!!";
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break;
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default:
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monthString = "Some other month";
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break;
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}
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///////////////////////////////////////
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// Converting Data Types And Typecasting
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///////////////////////////////////////
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// Converting data
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// Convert String To Integer
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// this will throw a FormatException on failure
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int.Parse("123");//returns an integer version of "123"
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// try parse will default to type default on failure
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// in this case: 0
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int tryInt;
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if (int.TryParse("123", out tryInt)) // Function is boolean
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Console.WriteLine(tryInt); // 123
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// Convert Integer To String
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// Convert class has a number of methods to facilitate conversions
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Convert.ToString(123);
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// or
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tryInt.ToString();
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// Casting
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// Cast decimal 15 to a int
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// and then implicitly cast to long
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long x = (int) 15M;
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}
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///////////////////////////////////////
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// CLASSES - see definitions at end of file
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///////////////////////////////////////
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public static void Classes()
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{
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// See Declaration of objects at end of file
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// Use new to instantiate a class
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Bicycle trek = new Bicycle();
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// Call object methods
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trek.SpeedUp(3); // You should always use setter and getter methods
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trek.Cadence = 100;
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// ToString is a convention to display the value of this Object.
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Console.WriteLine("trek info: " + trek.Info());
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// Instantiate a new Penny Farthing
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PennyFarthing funbike = new PennyFarthing(1, 10);
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Console.WriteLine("funbike info: " + funbike.Info());
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Console.Read();
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} // End main method
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// CONSOLE ENTRY A console application must have a main method as an entry point
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public static void Main(string[] args)
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{
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OtherInterestingFeatures();
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}
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//
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// INTERESTING FEATURES
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//
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// DEFAULT METHOD SIGNATURES
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public // Visibility
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static // Allows for direct call on class without object
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int // Return Type,
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MethodSignatures(
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int maxCount, // First variable, expects an int
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int count = 0, // will default the value to 0 if not passed in
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int another = 3,
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params string[] otherParams // captures all other parameters passed to method
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)
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{
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return -1;
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}
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// Methods can have the same name, as long as the signature is unique
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// A method that differs only in return type is not unique
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public static void MethodSignatures(
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ref int maxCount, // Pass by reference
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out int count)
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{
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count = 15; // out param must be assigned before control leaves the method
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}
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// GENERICS
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// The classes for TKey and TValue is specified by the user calling this function.
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// This method emulates the SetDefault of Python
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public static TValue SetDefault<TKey, TValue>(
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IDictionary<TKey, TValue> dictionary,
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TKey key,
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TValue defaultItem)
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{
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TValue result;
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if (!dictionary.TryGetValue(key, out result))
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return dictionary[key] = defaultItem;
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return result;
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}
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// You can narrow down the objects that are passed in
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public static void IterateAndPrint<T>(T toPrint) where T: IEnumerable<int>
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{
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// We can iterate, since T is a IEnumerable
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foreach (var item in toPrint)
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// Item is an int
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Console.WriteLine(item.ToString());
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}
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public static void OtherInterestingFeatures()
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{
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// OPTIONAL PARAMETERS
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MethodSignatures(3, 1, 3, "Some", "Extra", "Strings");
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MethodSignatures(3, another: 3); // explicity set a parameter, skipping optional ones
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// BY REF AND OUT PARAMETERS
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int maxCount = 0, count; // ref params must have value
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MethodSignatures(ref maxCount, out count);
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// EXTENSION METHODS
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int i = 3;
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i.Print(); // Defined below
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// NULLABLE TYPES - great for database interaction / return values
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// any value type (i.e. not a class) can be made nullable by suffixing a ?
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// <type>? <var name> = <value>
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int? nullable = null; // short hand for Nullable<int>
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Console.WriteLine("Nullable variable: " + nullable);
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bool hasValue = nullable.HasValue; // true if not null
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// ?? is syntactic sugar for specifying default value (coalesce)
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// in case variable is null
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int notNullable = nullable ?? 0; // 0
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// IMPLICITLY TYPED VARIABLES - you can let the compiler work out what the type is:
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var magic = "magic is a string, at compile time, so you still get type safety";
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// magic = 9; will not work as magic is a string, not an int
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// GENERICS
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//
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var phonebook = new Dictionary<string, string>() {
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{"Sarah", "212 555 5555"} // Add some entries to the phone book
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};
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// Calling SETDEFAULT defined as a generic above
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Console.WriteLine(SetDefault<string,string>(phonebook, "Shaun", "No Phone")); // No Phone
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// nb, you don't need to specify the TKey and TValue since they can be
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// derived implicitly
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Console.WriteLine(SetDefault(phonebook, "Sarah", "No Phone")); // 212 555 5555
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// LAMBDA EXPRESSIONS - allow you to write code in line
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Func<int, int> square = (x) => x * x; // Last T item is the return value
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Console.WriteLine(square(3)); // 9
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// ERROR HANDLING - coping with an uncertain world
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try
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{
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var funBike = PennyFarthing.CreateWithGears(6);
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// will no longer execute because CreateWithGears throws an exception
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string some = "";
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if (true) some = null;
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some.ToLower(); // throws a NullReferenceException
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}
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catch (NotSupportedException)
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{
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Console.WriteLine("Not so much fun now!");
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}
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catch (Exception ex) // catch all other exceptions
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{
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throw new ApplicationException("It hit the fan", ex);
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// throw; // A rethrow that preserves the callstack
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}
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// catch { } // catch-all without capturing the Exception
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finally
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{
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// executes after try or catch
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}
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// DISPOSABLE RESOURCES MANAGEMENT - let you handle unmanaged resources easily.
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// Most of objects that access unmanaged resources (file handle, device contexts, etc.)
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// implement the IDisposable interface. The using statement takes care of
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// cleaning those IDisposable objects for you.
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using (StreamWriter writer = new StreamWriter("log.txt"))
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{
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writer.WriteLine("Nothing suspicious here");
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// At the end of scope, resources will be released.
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// Even if an exception is thrown.
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}
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// PARALLEL FRAMEWORK
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// http://blogs.msdn.com/b/csharpfaq/archive/2010/06/01/parallel-programming-in-net-framework-4-getting-started.aspx
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var websites = new string[] {
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"http://www.google.com", "http://www.reddit.com",
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"http://www.shaunmccarthy.com"
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};
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var responses = new Dictionary<string, string>();
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// Will spin up separate threads for each request, and join on them
|
||
// before going to the next step!
|
||
Parallel.ForEach(websites,
|
||
new ParallelOptions() {MaxDegreeOfParallelism = 3}, // max of 3 threads
|
||
website =>
|
||
{
|
||
// Do something that takes a long time on the file
|
||
using (var r = WebRequest.Create(new Uri(website)).GetResponse())
|
||
{
|
||
responses[website] = r.ContentType;
|
||
}
|
||
});
|
||
|
||
// This won't happen till after all requests have been completed
|
||
foreach (var key in responses.Keys)
|
||
Console.WriteLine("{0}:{1}", key, responses[key]);
|
||
|
||
// DYNAMIC OBJECTS (great for working with other languages)
|
||
dynamic student = new ExpandoObject();
|
||
student.FirstName = "First Name"; // No need to define class first!
|
||
|
||
// You can even add methods (returns a string, and takes in a string)
|
||
student.Introduce = new Func<string, string>(
|
||
(introduceTo) => string.Format("Hey {0}, this is {1}", student.FirstName, introduceTo));
|
||
Console.WriteLine(student.Introduce("Beth"));
|
||
|
||
// IQUERYABLE<T> - almost all collections implement this, which gives you a lot of
|
||
// very useful Map / Filter / Reduce style methods
|
||
var bikes = new List<Bicycle>();
|
||
bikes.Sort(); // Sorts the array
|
||
bikes.Sort((b1, b2) => b1.Wheels.CompareTo(b2.Wheels)); // Sorts based on wheels
|
||
var result = bikes
|
||
.Where(b => b.Wheels > 3) // Filters - chainable (returns IQueryable of previous type)
|
||
.Where(b => b.IsBroken && b.HasTassles)
|
||
.Select(b => b.ToString()); // Map - we only this selects, so result is a IQueryable<string>
|
||
|
||
var sum = bikes.Sum(b => b.Wheels); // Reduce - sums all the wheels in the collection
|
||
|
||
// Create a list of IMPLICIT objects based on some parameters of the bike
|
||
var bikeSummaries = bikes.Select(b=>new { Name = b.Name, IsAwesome = !b.IsBroken && b.HasTassles });
|
||
// Hard to show here, but you get type ahead completion since the compiler can implicitly work
|
||
// out the types above!
|
||
foreach (var bikeSummary in bikeSummaries.Where(b => b.IsAwesome))
|
||
Console.WriteLine(bikeSummary.Name);
|
||
|
||
// ASPARALLEL
|
||
// And this is where things get wicked - combines linq and parallel operations
|
||
var threeWheelers = bikes.AsParallel().Where(b => b.Wheels == 3).Select(b => b.Name);
|
||
// this will happen in parallel! Threads will automagically be spun up and the
|
||
// results divvied amongst them! Amazing for large datasets when you have lots of
|
||
// cores
|
||
|
||
// LINQ - maps a store to IQueryable<T> objects, with delayed execution
|
||
// e.g. LinqToSql - maps to a database, LinqToXml maps to an xml document
|
||
var db = new BikeRepository();
|
||
|
||
// execution is delayed, which is great when querying a database
|
||
var filter = db.Bikes.Where(b => b.HasTassles); // no query run
|
||
if (42 > 6) // You can keep adding filters, even conditionally - great for "advanced search" functionality
|
||
filter = filter.Where(b => b.IsBroken); // no query run
|
||
|
||
var query = filter
|
||
.OrderBy(b => b.Wheels)
|
||
.ThenBy(b => b.Name)
|
||
.Select(b => b.Name); // still no query run
|
||
|
||
// Now the query runs, but opens a reader, so only populates are you iterate through
|
||
foreach (string bike in query)
|
||
Console.WriteLine(result);
|
||
|
||
|
||
|
||
}
|
||
|
||
} // End LearnCSharp class
|
||
|
||
// You can include other classes in a .cs file
|
||
|
||
public static class Extensions
|
||
{
|
||
// EXTENSION FUNCTIONS
|
||
public static void Print(this object obj)
|
||
{
|
||
Console.WriteLine(obj.ToString());
|
||
}
|
||
}
|
||
|
||
// Class Declaration Syntax:
|
||
// <public/private/protected/internal> class <class name>{
|
||
// //data fields, constructors, functions all inside.
|
||
// //functions are called as methods in Java.
|
||
// }
|
||
|
||
public class Bicycle
|
||
{
|
||
// Bicycle's Fields/Variables
|
||
public int Cadence // Public: Can be accessed from anywhere
|
||
{
|
||
get // get - define a method to retrieve the property
|
||
{
|
||
return _cadence;
|
||
}
|
||
set // set - define a method to set a proprety
|
||
{
|
||
_cadence = value; // Value is the value passed in to the setter
|
||
}
|
||
}
|
||
private int _cadence;
|
||
|
||
protected virtual int Gear // Protected: Accessible from the class and subclasses
|
||
{
|
||
get; // creates an auto property so you don't need a member field
|
||
set;
|
||
}
|
||
|
||
internal int Wheels // Internal: Accessible from within the assembly
|
||
{
|
||
get;
|
||
private set; // You can set modifiers on the get/set methods
|
||
}
|
||
|
||
int _speed; // Everything is private by default: Only accessible from within this class.
|
||
// can also use keyword private
|
||
public string Name { get; set; }
|
||
|
||
// Enum is a value type that consists of a set of named constants
|
||
// It is really just mapping a name to a value (an int, unless specified otherwise).
|
||
// The approved types for an enum are byte, sbyte, short, ushort, int, uint, long, or ulong.
|
||
// An enum can't contain the same value twice.
|
||
public enum BikeBrand
|
||
{
|
||
AIST,
|
||
BMC,
|
||
Electra = 42, //you can explicitly set a value to a name
|
||
Gitane // 43
|
||
}
|
||
// We defined this type inside a Bicycle class, so it is a nested type
|
||
// Code outside of this class should reference this type as Bicycle.Brand
|
||
|
||
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);
|
||
public static int BicyclesCreated { get; set; }
|
||
|
||
// readonly values are set at run time
|
||
// they can only be assigned upon declaration or in a constructor
|
||
readonly bool _hasCardsInSpokes = false; // read-only private
|
||
|
||
// Constructors are a way of creating classes
|
||
// This is a default constructor
|
||
public Bicycle()
|
||
{
|
||
this.Gear = 1; // you can access members of the object with the keyword this
|
||
Cadence = 50; // but you don't always need it
|
||
_speed = 5;
|
||
Name = "Bontrager";
|
||
Brand = BikeBrand.AIST;
|
||
BicyclesCreated++;
|
||
}
|
||
|
||
// This is a specified constructor (it contains arguments)
|
||
public Bicycle(int startCadence, int startSpeed, int startGear,
|
||
string name, bool hasCardsInSpokes, BikeBrand brand)
|
||
: base() // calls base first
|
||
{
|
||
Gear = startGear;
|
||
Cadence = startCadence;
|
||
_speed = startSpeed;
|
||
Name = name;
|
||
_hasCardsInSpokes = hasCardsInSpokes;
|
||
Brand = brand;
|
||
}
|
||
|
||
// Constructors can be chained
|
||
public Bicycle(int startCadence, int startSpeed, BikeBrand brand) :
|
||
this(startCadence, startSpeed, 0, "big wheels", true, brand)
|
||
{
|
||
}
|
||
|
||
// Function Syntax:
|
||
// <public/private/protected> <return type> <function name>(<args>)
|
||
|
||
// classes can implement getters and setters for their fields
|
||
// or they can implement properties (this is the preferred way in C#)
|
||
|
||
// Method parameters can have default values.
|
||
// In this case, methods can be called with these parameters omitted
|
||
public void SpeedUp(int increment = 1)
|
||
{
|
||
_speed += increment;
|
||
}
|
||
|
||
public void SlowDown(int decrement = 1)
|
||
{
|
||
_speed -= decrement;
|
||
}
|
||
|
||
// properties get/set values
|
||
// when only data needs to be accessed, consider using properties.
|
||
// properties may have either get or set, or both
|
||
private bool _hasTassles; // private variable
|
||
public bool HasTassles // public accessor
|
||
{
|
||
get { return _hasTassles; }
|
||
set { _hasTassles = value; }
|
||
}
|
||
|
||
// You can also define an automatic property in one line
|
||
// this syntax will create a backing field automatically.
|
||
// You can set an access modifier on either the getter or the setter (or both)
|
||
// to restrict its access:
|
||
public bool IsBroken { get; private set; }
|
||
|
||
// Properties can be auto-implemented
|
||
public int FrameSize
|
||
{
|
||
get;
|
||
// you are able to specify access modifiers for either get or set
|
||
// this means only Bicycle class can call set on Framesize
|
||
private set;
|
||
}
|
||
|
||
// It's also possible to define custom Indexers on objects.
|
||
// 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" };
|
||
|
||
public string this[int i]
|
||
{
|
||
get {
|
||
return passengers[i];
|
||
}
|
||
|
||
set {
|
||
return passengers[i] = value;
|
||
}
|
||
}
|
||
|
||
//Method to display the attribute values of this Object.
|
||
public virtual string Info()
|
||
{
|
||
return "Gear: " + Gear +
|
||
" Cadence: " + Cadence +
|
||
" Speed: " + _speed +
|
||
" Name: " + Name +
|
||
" Cards in Spokes: " + (_hasCardsInSpokes ? "yes" : "no") +
|
||
"\n------------------------------\n"
|
||
;
|
||
}
|
||
|
||
// Methods can also be static. It can be useful for helper methods
|
||
public static bool DidWeCreateEnoughBycles()
|
||
{
|
||
// Within a static method, we only can reference static class members
|
||
return BicyclesCreated > 9000;
|
||
} // If your class only needs static members, consider marking the class itself as static.
|
||
|
||
|
||
} // end class Bicycle
|
||
|
||
// PennyFarthing is a subclass of Bicycle
|
||
class PennyFarthing : Bicycle
|
||
{
|
||
// (Penny Farthings are those bicycles with the big front wheel.
|
||
// They have no gears.)
|
||
|
||
// calling parent constructor
|
||
public PennyFarthing(int startCadence, int startSpeed) :
|
||
base(startCadence, startSpeed, 0, "PennyFarthing", true, BikeBrand.Electra)
|
||
{
|
||
}
|
||
|
||
protected override int Gear
|
||
{
|
||
get
|
||
{
|
||
return 0;
|
||
}
|
||
set
|
||
{
|
||
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 ";
|
||
result += base.ToString(); // Calling the base version of the method
|
||
return result;
|
||
}
|
||
}
|
||
|
||
// Interfaces only contain signatures of the members, without the implementation.
|
||
interface IJumpable
|
||
{
|
||
void Jump(int meters); // all interface members are implicitly public
|
||
}
|
||
|
||
interface IBreakable
|
||
{
|
||
bool Broken { get; } // interfaces can contain properties as well as methods & events
|
||
}
|
||
|
||
// Class can inherit only one other class, but can implement any amount of interfaces
|
||
class MountainBike : Bicycle, IJumpable, IBreakable
|
||
{
|
||
int damage = 0;
|
||
|
||
public void Jump(int meters)
|
||
{
|
||
damage += meters;
|
||
}
|
||
|
||
public bool Broken
|
||
{
|
||
get
|
||
{
|
||
return damage > 100;
|
||
}
|
||
}
|
||
}
|
||
|
||
/// <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
|
||
/// </summary>
|
||
public class BikeRepository : DbContext
|
||
{
|
||
public BikeRepository()
|
||
: base()
|
||
{
|
||
}
|
||
|
||
public DbSet<Bicycle> Bikes { get; set; }
|
||
}
|
||
} // End Namespace
|
||
```
|
||
|
||
## Topics Not Covered
|
||
|
||
* Attributes
|
||
* 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
|
||
|
||
* [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)
|