mirror of
https://github.com/adambard/learnxinyminutes-docs.git
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Added Interesting Features (and fixed / cleaned up other code)
Fixed syntax errors, made items more succinct, and added a section of interesting features in c#
This commit is contained in:
Shaun McCarthy
parent
661d9481c8
commit
0cee5bd79a
@ -3,8 +3,8 @@ language: c#
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contributors:
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- ["Irfan Charania", "https://github.com/irfancharania"]
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- ["Max Yankov", "https://github.com/golergka"]
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- ["Melvyn Laïly", "http://x2a.yt"]
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filename: LearnCSharp.cs
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- ["Melvyn Laïly", "http://x2a.yt"]
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- ["Shaun McCarthy", "http://www.shaunmccarthy.com"]
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---
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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.
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@ -23,7 +23,12 @@ Multi-line comments look like this
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// Specify namespaces application will be using
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using System;
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using System.Collections.Generic;
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using System.Data.Entity;
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using System.Dynamic;
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using System.Linq;
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using System.Linq.Expressions;
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using System.Net;
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using System.Threading.Tasks;
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// defines scope to organize code into "packages"
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namespace Learning
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@ -32,8 +37,8 @@ namespace Learning
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// you're allowed to do otherwise, but shouldn't for sanity.
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public class LearnCSharp
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{
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// 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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// BASIC SYNTAX - skip to INTERESTING FEATURES if you have used Java or C++ before
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public static void Syntax()
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{
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// Use Console.WriteLine to print lines
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Console.WriteLine("Hello World");
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@ -46,7 +51,6 @@ namespace Learning
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Console.Write("Hello ");
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Console.Write("World");
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///////////////////////////////////////////////////
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// Types & Variables
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//
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@ -61,140 +65,83 @@ namespace Learning
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// (0 <= byte <= 255)
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byte fooByte = 100;
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// Short - Signed 16-bit integer
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// (-32,768 <= short <= 32,767)
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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 - Unsigned 16-bit integer
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// (0 <= ushort <= 65,535)
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ushort fooUshort = 10000;
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// Integer - Signed 32-bit integer
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// (-2,147,483,648 <= int <= 2,147,483,647)
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int fooInt = 1;
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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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// Uinteger - Unsigned 32-bit integer
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// (0 <= uint <= 4,294,967,295)
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uint fooUint = 1;
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// Long - Signed 64-bit integer
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// (-9,223,372,036,854,775,808 <= long <= 9,223,372,036,854,775,807)
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long fooLong = 100000L;
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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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// anything without is treated as int or uint depending on size.
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// Ulong - Unsigned 64-bit integer
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// (0 <= ulong <= 18,446,744,073,709,551,615)
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ulong fooUlong = 100000L;
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// Float - Single-precision 32-bit IEEE 754 Floating Point
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// Precision: 7 digits
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float fooFloat = 234.5f;
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// f is used to denote that this variable value is of type float;
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// otherwise it is treated as double.
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// Double - Double-precision 64-bit IEEE 754 Floating Point
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// Precision: 15-16 digits
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double fooDouble = 123.4;
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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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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;
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bool barBoolean = 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 -- unlike the previous base types which are all value types,
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// a string is a reference type. That is, you can set it to null
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string fooString = "My string is here!";
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// a string is a reference type. That is, you can set it to null
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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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// You can access each character of the string with an indexer:
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char charFromString = fooString[1]; // 'y'
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// Strings are immutable: you can't do fooString[1] = 'X';
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// formatting
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// You can access each character of the string with an indexer:
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char charFromString = fooString[1]; // 'y'
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// Strings are immutable: you can't do fooString[1] = 'X';
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// Compare strings with current culture, ignoring case
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string.Compare(fooString, "x", StringComparison.CurrentCultureIgnoreCase);
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// Formatting, based on sprintf
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string fooFs = string.Format("Check Check, {0} {1}, {0} {1:0.0}", 1, 2);
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Console.WriteLine(fooFormattedString);
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// formatting dates
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// Dates & Formatting
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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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// \n is an escaped character that starts a new line
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string barString = "Printing on a new line?\nNo Problem!";
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Console.WriteLine(barString);
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// it can be written prettier by using the @ symbol
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// You can split a string over two lines with the @ symbol. To escape " use ""
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string bazString = @"Here's some stuff
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on a new line!";
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Console.WriteLine(bazString);
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// quotes need to be escaped
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// use \" normally
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string quotedString = "some \"quoted\" stuff";
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Console.WriteLine(quotedString);
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// use "" when strings start with @
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string quotedString2 = @"some MORE ""quoted"" stuff";
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Console.WriteLine(quotedString2);
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on a new line! ""Wow!"", the masses cried";
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// Use const or read-only to make a variable immutable
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// const values are calculated at compile time
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const int HOURS_I_WORK_PER_WEEK = 9001;
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// Nullable types
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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;
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Console.WriteLine("Nullable variable: " + nullable);
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// In order to use nullable's value, you have to use Value property
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// or to explicitly cast it
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DateTime? nullableDate = null;
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// The previous line would not have compiled without the '?'
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// because DateTime is a value type
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// <type>? is equivalent to writing Nullable<type>
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Nullable<DateTime> otherNullableDate = nullableDate;
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nullableDate = DateTime.Now;
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Console.WriteLine("Nullable value is: " + nullableDate.Value + " or: " + (DateTime) nullableDate );
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// ?? is syntactic sugar for specifying default value
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// in case variable is null
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int notNullable = nullable ?? 0;
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Console.WriteLine("Not nullable variable: " + notNullable);
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// Var - compiler will choose the most appropriate type based on value
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// Please note that this does not remove type safety.
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// In this case, the type of fooImplicit is known to be a bool at compile time
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var fooImplicit = true;
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///////////////////////////////////////////////////
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// Data Structures
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///////////////////////////////////////////////////
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Console.WriteLine("\n->Data Structures");
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// Arrays
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// Arrays - zero indexed
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// The array size must be decided upon declaration
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// The format for declaring an array is follows:
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// <datatype>[] <var name> = new <datatype>[<array size>];
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int[] intArray = new int[10];
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string[] stringArray = new string[1];
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bool[] boolArray = new bool[100];
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// Another way to declare & initialize an array
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int[] y = { 9000, 1000, 1337 };
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// Indexing an array - Accessing an element
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Console.WriteLine("intArray @ 0: " + intArray[0]);
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// Arrays are zero-indexed and mutable.
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// Arrays are mutable.
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intArray[1] = 1;
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Console.WriteLine("intArray @ 1: " + intArray[1]); // => 1
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// Lists
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// Lists are used more frequently than arrays as they are more flexible
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@ -202,28 +149,21 @@ namespace Learning
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// List<datatype> <var name> = new List<datatype>();
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List<int> intList = new List<int>();
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List<string> stringList = new List<string>();
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// Another way to declare & initialize a list
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List<int> z = new List<int> { 9000, 1000, 1337 };
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// Indexing a list - Accessing an element
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// Lists are zero-indexed and mutable.
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Console.WriteLine("z @ 0: " + z[2]);
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List<int> z = new List<int> { 9000, 1000, 1337 }; // intialize
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// The <> are for templates - Check out the cool stuff section
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// Lists don't default to a value;
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// A value must be added before accessing the index
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intList.Add(1);
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Console.WriteLine("intList @ 0: " + intList[0]);
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// Others data structures to check out:
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//
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// Stack/Queue
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// Dictionary (an implementation of a hash map)
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// HashSet
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// Read-only Collections
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// Tuple (.Net 4+)
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///////////////////////////////////////
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// Operators
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///////////////////////////////////////
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@ -232,10 +172,7 @@ namespace Learning
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int i1 = 1, i2 = 2; // Shorthand for multiple declarations
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// Arithmetic is straightforward
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Console.WriteLine("1+2 = " + (i1 + i2)); // => 3
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Console.WriteLine("2-1 = " + (i2 - i1)); // => 1
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Console.WriteLine("2*1 = " + (i2 * i1)); // => 2
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Console.WriteLine("1/2 = " + (i1 / i2)); // => 0 (0.5 truncated down)
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Console.WriteLine(i1 + i2 - i1 * 3 / 7); //
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// Modulo
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Console.WriteLine("11%3 = " + (11 % 3)); // => 2
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@ -266,7 +203,6 @@ namespace Learning
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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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// Control Structures
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///////////////////////////////////////
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@ -291,50 +227,37 @@ namespace Learning
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// A simple if/else can be written as follows
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// <condition> ? <true> : <false>
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string isTrue = (true) ? "True" : "False";
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Console.WriteLine("Ternary demo: " + isTrue);
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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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//Console.WriteLine(fooWhile);
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//Increment the counter
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//Iterated 99 times, fooWhile 0->99
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fooWhile++;
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}
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Console.WriteLine("fooWhile Value: " + fooWhile);
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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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//Console.WriteLine(fooDoWhile);
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//Increment the counter
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//Iterated 99 times, fooDoWhile 0->99
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fooDoWhile++;
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} while (fooDoWhile < 100);
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Console.WriteLine("fooDoWhile Value: " + fooDoWhile);
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// For Loop
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int fooFor;
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//for loop structure => for(<start_statement>; <conditional>; <step>)
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for (fooFor = 0; fooFor < 10; fooFor++)
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for (int fooFor = 0; fooFor < 10; fooFor++)
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{
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//Console.WriteLine(fooFor);
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//Iterated 10 times, fooFor 0->9
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}
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Console.WriteLine("fooFor Value: " + fooFor);
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// For Each Loop
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// For Each Loop
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// foreach loop structure => foreach(<iteratorType> <iteratorName> in <enumerable>)
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// The foreach loop loops over any object implementing IEnumerable or IEnumerable<T>
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// All the collection types (Array, List, Dictionary...) in the .Net framework
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// implement one or both of these interfaces.
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// (The ToCharArray() could be removed, because a string also implements IEnumerable)
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// The foreach loop loops over any object implementing IEnumerable or IEnumerable<T>
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// All the collection types (Array, List, Dictionary...) in the .Net framework
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// implement one or both of these interfaces.
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// (The ToCharArray() could be removed, because a string also implements IEnumerable)
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foreach (char character in "Hello World".ToCharArray())
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{
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//Console.WriteLine(character);
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//Iterated over all the characters in the string
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}
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@ -356,20 +279,18 @@ namespace Learning
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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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// 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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Console.WriteLine("Switch Case Result: " + monthString);
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///////////////////////////////////////
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// Converting Data Types And Typecasting
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@ -384,46 +305,227 @@ namespace Learning
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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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int.TryParse("123", out tryInt);
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if (int.TryParse("123", out tryInt)) // Funciton 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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}
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///////////////////////////////////////
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// Classes And Functions
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///////////////////////////////////////
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Console.WriteLine("\n->Classes & Functions");
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// (definition of the Bicycle class follows)
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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.setCadence(100);
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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.ToString());
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// Instantiate another new Bicycle
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Bicycle octo = new Bicycle(5, 10);
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Console.WriteLine("octo info: " + octo.ToString());
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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.ToString());
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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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public static void MethodSignature(string maxCount)
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{
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}
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// TEMPLATES
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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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// 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
|
||||
// any value type (i.e. not a class) can be made nullable by suffixing a ?
|
||||
// <type>? <var name> = <value>
|
||||
int? nullable = null; // short hand for Nullable<int>
|
||||
Console.WriteLine("Nullable variable: " + nullable);
|
||||
bool hasValue = nullable.HasValue; // true if not null
|
||||
|
||||
// ?? is syntactic sugar for specifying default value (coalesce)
|
||||
// in case variable is null
|
||||
int notNullable = nullable ?? 0; // 0
|
||||
|
||||
// IMPLICITLY TYPED VARIABLES - you can let the compiler work out what the type is:
|
||||
var magic = "magic is a string, at compile time, so you still get type safety";
|
||||
// magic = 9; will not work as magic is a string, not an int
|
||||
|
||||
// TEMPLATES
|
||||
var phonebook = new Dictionary<string, string>() {
|
||||
{"Sarah", "212 555 5555"} // Add some entries to the phone book
|
||||
};
|
||||
|
||||
// Calling SETDEFAULT defined as a template above
|
||||
Console.WriteLine(SetDefault<string,string>(phonebook, "Shaun", "No Phone")); // No Phone
|
||||
// nb, you don't need to specify the TKey and TValue since they can be
|
||||
// derived implicitly
|
||||
Console.WriteLine(SetDefault(phonebook, "Sarah", "No Phone")); // 212 555 5555
|
||||
|
||||
// LAMBDA EXPRESSIONS - allow you to write code in line
|
||||
Func<int, int> square = (x) => x * x; // Last T item is the return value
|
||||
Console.WriteLine(square(3)); // 9
|
||||
|
||||
// PARALLEL FRAMEWORK
|
||||
// http://blogs.msdn.com/b/csharpfaq/archive/2010/06/01/parallel-programming-in-net-framework-4-getting-started.aspx
|
||||
var websites = new string[] {
|
||||
"http://www.google.com", "http://www.reddit.com",
|
||||
"http://www.shaunmccarthy.com"
|
||||
};
|
||||
var responses = new Dictionary<string, string>();
|
||||
|
||||
// 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 BikeRespository();
|
||||
|
||||
// execution is delayed, which is great when querying a database
|
||||
var fitler = db.Bikes.Where(b => b.HasTassles); // no query run
|
||||
if (42 > 6) // You can keep adding filters, even conditionally - great for "advanced search" functionality
|
||||
fitler = fitler.Where(b => b.IsBroken); // no query run
|
||||
|
||||
var query = fitler
|
||||
.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>{
|
||||
@ -434,64 +536,88 @@ namespace Learning
|
||||
public class Bicycle
|
||||
{
|
||||
// Bicycle's Fields/Variables
|
||||
public int cadence; // Public: Can be accessed from anywhere
|
||||
private int _speed; // Private: Only accessible from within the class
|
||||
protected int gear; // Protected: Accessible from the class and subclasses
|
||||
internal int wheels; // Internal: Accessible from within the assembly
|
||||
string name; // Everything is private by default: Only accessible from within this class
|
||||
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 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 privatee
|
||||
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 Brand
|
||||
// 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
|
||||
Electra = 42, //you can explicitly set a value to a name
|
||||
Gitane
|
||||
}
|
||||
// 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 Brand brand; // After declaring an enum type, we can declare the field of this type
|
||||
public BikeBrand Brand; // After declaring an enum type, we can declare the field of this type
|
||||
|
||||
// Static members belong to the type itself rather then specific object.
|
||||
static public int bicyclesCreated = 0;
|
||||
// You can access them without a reference to any object:
|
||||
// Console.WriteLine("Bicycles created: " + Bicycle.bicyclesCreated);
|
||||
static public int BicyclesCreated = 0;
|
||||
|
||||
// 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
|
||||
readonly bool _hasCardsInSpokes = false; // read-only private
|
||||
|
||||
// Constructors are a way of creating classes
|
||||
// This is a default constructor
|
||||
private Bicycle()
|
||||
public Bicycle()
|
||||
{
|
||||
gear = 1;
|
||||
cadence = 50;
|
||||
this.Gear = 1; // you can access mmebers of the object with the keyword this
|
||||
Cadence = 50; // but you don't always need it
|
||||
_speed = 5;
|
||||
name = "Bontrager";
|
||||
brand = Brand.AIST;
|
||||
bicyclesCreated++;
|
||||
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, Brand brand)
|
||||
string name, bool hasCardsInSpokes, BikeBrand brand)
|
||||
: base() // calls base first
|
||||
{
|
||||
this.gear = startGear; // "this" keyword denotes the current object
|
||||
this.cadence = startCadence;
|
||||
this._speed = startSpeed;
|
||||
this.name = name; // it can be useful when there's a name conflict
|
||||
this.hasCardsInSpokes = hasCardsInSpokes;
|
||||
this.brand = brand;
|
||||
Gear = startGear;
|
||||
Cadence = startCadence;
|
||||
_speed = startSpeed;
|
||||
Name = name;
|
||||
_hasCardsInSpokes = hasCardsInSpokes;
|
||||
Brand = brand;
|
||||
}
|
||||
|
||||
// Constructors can be chained
|
||||
public Bicycle(int startCadence, int startSpeed, Brand brand) :
|
||||
this(startCadence, startSpeed, 0, "big wheels", true)
|
||||
public Bicycle(int startCadence, int startSpeed, BikeBrand brand) :
|
||||
this(startCadence, startSpeed, 0, "big wheels", true, brand)
|
||||
{
|
||||
}
|
||||
|
||||
@ -501,27 +627,8 @@ namespace Learning
|
||||
// classes can implement getters and setters for their fields
|
||||
// or they can implement properties (this is the preferred way in C#)
|
||||
|
||||
// Method declaration syntax:
|
||||
// <scope> <return type> <method name>(<args>)
|
||||
public int GetCadence()
|
||||
{
|
||||
return cadence;
|
||||
}
|
||||
|
||||
// void methods require no return statement
|
||||
public void SetCadence(int newValue)
|
||||
{
|
||||
cadence = newValue;
|
||||
}
|
||||
|
||||
// virtual keyword indicates this method can be overridden in a derived class
|
||||
public virtual void SetGear(int newValue)
|
||||
{
|
||||
gear = newValue;
|
||||
}
|
||||
|
||||
// Method parameters can have default values.
|
||||
// In this case, methods can be called with these parameters omitted
|
||||
// In this case, methods can be called with these parameters omitted
|
||||
public void SpeedUp(int increment = 1)
|
||||
{
|
||||
_speed += increment;
|
||||
@ -541,12 +648,12 @@ namespace Learning
|
||||
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; }
|
||||
|
||||
// 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
|
||||
@ -558,13 +665,13 @@ namespace Learning
|
||||
}
|
||||
|
||||
//Method to display the attribute values of this Object.
|
||||
public override string ToString()
|
||||
public virtual string Info()
|
||||
{
|
||||
return "gear: " + gear +
|
||||
" cadence: " + cadence +
|
||||
" speed: " + _speed +
|
||||
" name: " + name +
|
||||
" cards in spokes: " + (hasCardsInSpokes ? "yes" : "no") +
|
||||
return "Gear: " + Gear +
|
||||
" Cadence: " + Cadence +
|
||||
" Speed: " + _speed +
|
||||
" Name: " + Name +
|
||||
" Cards in Spokes: " + (_hasCardsInSpokes ? "yes" : "no") +
|
||||
"\n------------------------------\n"
|
||||
;
|
||||
}
|
||||
@ -573,9 +680,10 @@ namespace Learning
|
||||
public static bool DidWeCreateEnoughBycles()
|
||||
{
|
||||
// Within a static method, we only can reference static class members
|
||||
return bicyclesCreated > 9000;
|
||||
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
|
||||
@ -586,20 +694,27 @@ namespace Learning
|
||||
|
||||
// calling parent constructor
|
||||
public PennyFarthing(int startCadence, int startSpeed) :
|
||||
base(startCadence, startSpeed, 0, "PennyFarthing", true)
|
||||
base(startCadence, startSpeed, 0, "PennyFarthing", true, BikeBrand.Electra)
|
||||
{
|
||||
}
|
||||
|
||||
public override void SetGear(int gear)
|
||||
protected override int Gear
|
||||
{
|
||||
gear = 0;
|
||||
get
|
||||
{
|
||||
return 0;
|
||||
}
|
||||
set
|
||||
{
|
||||
throw new ArgumentException("You can't change gears on a PennyFarthing");
|
||||
}
|
||||
}
|
||||
|
||||
public override string ToString()
|
||||
public override string Info()
|
||||
{
|
||||
string result = "PennyFarthing bicycle ";
|
||||
result += base.ToString(); // Calling the base version of the method
|
||||
return reuslt;
|
||||
return result;
|
||||
}
|
||||
}
|
||||
|
||||
@ -624,7 +739,7 @@ namespace Learning
|
||||
damage += meters;
|
||||
}
|
||||
|
||||
public void Broken
|
||||
public bool Broken
|
||||
{
|
||||
get
|
||||
{
|
||||
@ -632,24 +747,34 @@ namespace Learning
|
||||
}
|
||||
}
|
||||
}
|
||||
} // End Namespace
|
||||
|
||||
/// <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 BikeRespository : DbSet
|
||||
{
|
||||
public BikeRespository()
|
||||
: base()
|
||||
{
|
||||
}
|
||||
|
||||
public DbSet<Bicycle> Bikes { get; set; }
|
||||
}
|
||||
} // End Namespace
|
||||
```
|
||||
|
||||
## Topics Not Covered
|
||||
|
||||
* Flags
|
||||
* Attributes
|
||||
* Generics (T), Delegates, Func, Actions, lambda expressions
|
||||
* Static properties
|
||||
* Exceptions, Abstraction
|
||||
* LINQ
|
||||
* ASP.NET (Web Forms/MVC/WebMatrix)
|
||||
* Winforms
|
||||
* Windows Presentation Foundation (WPF)
|
||||
|
||||
|
||||
|
||||
## Further Reading
|
||||
|
||||
* [DotNetPerls](http://www.dotnetperls.com)
|
||||
|
||||
Loading…
Reference in New Issue
Block a user