diff options
Diffstat (limited to 'csharp.html.markdown')
| -rw-r--r-- | csharp.html.markdown | 83 |
1 files changed, 64 insertions, 19 deletions
diff --git a/csharp.html.markdown b/csharp.html.markdown index 55de415d..1471b833 100644 --- a/csharp.html.markdown +++ b/csharp.html.markdown @@ -1,11 +1,10 @@ --- - language: c# contributors: - ["Irfan Charania", "https://github.com/irfancharania"] - ["Max Yankov", "https://github.com/golergka"] + - ["Melvyn Laïly", "http://x2a.yt"] filename: LearnCSharp.cs - --- C# is an elegant and type-safe object-oriented language that enables developers to build a variety of secure and robust applications that run on the .NET Framework. @@ -97,17 +96,25 @@ namespace Learning // Double - Double-precision 64-bit IEEE 754 Floating Point // Precision: 15-16 digits double fooDouble = 123.4; + + // Decimal - a 128-bits data type, with more precision than other floating-point types, + // suited for financial and monetary calculations + decimal fooDecimal = 150.3m; - // Bool - true & false + // Boolean - true & false bool fooBoolean = true; bool barBoolean = false; // Char - A single 16-bit Unicode character char fooChar = 'A'; - // Strings + // Strings -- unlike the previous base types which are all value types, + // a string is a reference type. That is, you can set it to null string fooString = "My string is here!"; Console.WriteLine(fooString); + // You can access each character of the string with an indexer: + char charFromString = fooString[1]; // 'y' + // Strings are immutable: you can't do fooString[1] = 'X'; // formatting string fooFs = string.Format("Check Check, {0} {1}, {0} {1:0.0}", 1, 2); @@ -140,14 +147,21 @@ namespace Learning const int HOURS_I_WORK_PER_WEEK = 9001; // Nullable types - // any type can be made nullable by suffixing a ? + // any value type (i.e. not a class) can be made nullable by suffixing a ? // <type>? <var name> = <value> int? nullable = null; Console.WriteLine("Nullable variable: " + nullable); - // In order to use nullable's value, you have to use Value property or to explicitly cast it - string? nullableString = "not null"; - Console.WriteLine("Nullable value is: " + nullableString.Value + " or: " + (string) nullableString ); + // In order to use nullable's value, you have to use Value property + // or to explicitly cast it + DateTime? nullableDate = null; + // The previous line would not have compiled without the '?' + // because DateTime is a value type + // <type>? is equivalent to writing Nullable<type> + Nullable<DateTime> otherNullableDate = nullableDate; + + nullableDate = DateTime.Now; + Console.WriteLine("Nullable value is: " + nullableDate.Value + " or: " + (DateTime) nullableDate ); // ?? is syntactic sugar for specifying default value // in case variable is null @@ -155,6 +169,8 @@ namespace Learning Console.WriteLine("Not nullable variable: " + notNullable); // Var - compiler will choose the most appropriate type based on value + // Please note that this does not remove type safety. + // In this case, the type of fooImplicit is known to be a bool at compile time var fooImplicit = true; /////////////////////////////////////////////////// @@ -203,7 +219,7 @@ namespace Learning // Others data structures to check out: // // Stack/Queue - // Dictionary + // Dictionary (an implementation of a hash map) // Read-only Collections // Tuple (.Net 4+) @@ -237,7 +253,6 @@ namespace Learning ~ Unary bitwise complement << Signed left shift >> Signed right shift - >>> Unsigned right shift & Bitwise AND ^ Bitwise exclusive OR | Bitwise inclusive OR @@ -310,6 +325,18 @@ namespace Learning //Iterated 10 times, fooFor 0->9 } Console.WriteLine("fooFor Value: " + fooFor); + + // For Each Loop + // foreach loop structure => foreach(<iteratorType> <iteratorName> in <enumerable>) + // The foreach loop loops over any object implementing IEnumerable or IEnumerable<T> + // All the collection types (Array, List, Dictionary...) in the .Net framework + // implement one or both of these interfaces. + // (The ToCharArray() could be removed, because a string also implements IEnumerable) + foreach (char character in "Hello World".ToCharArray()) + { + //Console.WriteLine(character); + //Iterated over all the characters in the string + } // Switch Case // A switch works with the byte, short, char, and int data types. @@ -329,6 +356,14 @@ namespace Learning case 3: monthString = "March"; break; + // You can assign more than one case to an action + // But you can't add an action without a break before another case + // (if you want to do this, you would have to explicitly add a goto case x + case 6: + case 7: + case 8: + monthString = "Summer time!!"; + break; default: monthString = "Some other month"; break; @@ -337,7 +372,7 @@ namespace Learning /////////////////////////////////////// - // Converting Data Types And Typcasting + // Converting Data Types And Typecasting /////////////////////////////////////// // Converting data @@ -391,7 +426,7 @@ namespace Learning // Class Declaration Syntax: - // <public/private/protected> class <class name>{ + // <public/private/protected/internal> class <class name>{ // //data fields, constructors, functions all inside. // //functions are called as methods in Java. // } @@ -406,17 +441,20 @@ namespace Learning string name; // Everything is private by default: Only accessible from within this class // 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 { AIST, BMC, - Electra, + 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 declaing an enum type, we can declare the field of this type + public Brand 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; @@ -461,7 +499,7 @@ namespace Learning // <public/private/protected> <return type> <function name>(<args>) // classes can implement getters and setters for their fields - // or they can implement properties + // or they can implement properties (this is the preferred way in C#) // Method declaration syntax: // <scope> <return type> <method name>(<args>) @@ -476,13 +514,14 @@ namespace Learning cadence = newValue; } - // virtual keyword indicates this method can be overridden + // virtual keyword indicates this method can be overridden in a derived class public virtual void SetGear(int newValue) { gear = newValue; } - // Method parameters can have defaut values. In this case, methods can be called with these parameters omitted + // 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; @@ -502,6 +541,12 @@ 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; } // Properties can be auto-implemented public int FrameSize @@ -527,7 +572,7 @@ namespace Learning // 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 memebers + // 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. @@ -566,7 +611,7 @@ namespace Learning interface IBreakable { - bool Broken { get; } // interfaces can contain properties as well as methods, fields & events + 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 |