C# Cheat Sheet, Summaries of Designs and Groups

Download C# Cheat Sheet and more Summaries Designs and Groups in PDF only on Docsity! C# Cheat Sheet INTRODUCTION C# is a powerful Object Orientated language, for those coming from Java or C++ you should be able to pick up the syntax for C# quickly. A few points:  The language is case-sensitive (So A and a are different)  Lines terminate with semi-colons  Code is put in code blocks { }  Inline comments start with //  Block comments start with /* */  XML comments start with /// VARIABLES To declare a variable you specify the data type and variable name followed by a value. SYNTAX DataType variableName = value; NAMING RULES Variables must start with underscore or letter Variables cannot contain spaces variables can contain numbers Cannot contain symbols (accept underscore) EXAMPLE string Name = "thecodingguys"; int Year = 2013; I will use these two variables throughout. ARRAYS Arrays are similar to variables, but can hold more than one value. SYNTAX DataType[ ] ArrayName = { Comma Separated Values } // Array of any size DataType[] ArrayName = new DataType[3] {Command Separated Values } //Expects 3 values EXAMPLE string[] MyGamesOf2013 = {"GTAV", "Battlefield3"}; string[] MyMoveisOf2013 = new string[3] {"The Amazing Spiderman", "The Expendables 2", "Rise of the planet of the apes"}; Records Record structures allow you to store multiple data types under one identifier name. You can create an array of them to store lots of data Syntax Must be declared outside the of any method as a global public struct StructName { public string field1; public int field2; public string field3; public int field4; } Run within a method: StructName [] ArrayName = new StructName [20]; Example public struct Results { public string hometeam; public int hometeamscore; public string awayteam; public int awayteamscore; } Run within a method: Results[] results = new Results[20]; FOR LOOP Similar to the While Loop, but you specify when the loop will end. SYNTAX for (int i = 0; i < length; i++) { } EXAMPLE for (int i = 0; i <= 100; i++) { Console.WriteLine(i); } This prints out 1 to 100. The expression can be easily broken down like this: I = 0; I Is less than or equal to 100? (True) Increment I by 1 When I reaches 100 it will stop because I will no longer be less than100 and will equal 100 so the condition is false. FOR EACH The for each loop is used to loop around a collection. (Such as an array) SYNTAX foreach (var item in collection) { } EXAMPLE foreach (string movie in MyMoveisOf2013) { Console.WriteLine(movie); } Outputs all the elements in the MyMoviesOf2013 array. EXCEPTION Handling To catch any exceptions which are likely to occur you use a try catch block. SYNTAX try { } catch (Exception) { } EXAMPLE try { string result = "k"; Console.WriteLine(Convert.ToInt32(result) + 10); } catch (Exception ex) { Console.WriteLine(ex.Message); } The above code results in a format exception, because you can’t convert K to a number  METHODS SYNTAX public void MethodName() { //Does not return a value } public static void MethodName() { //Does not return a value, the class does not need to be initialized //for this method to be used. } public static DataType MethodName() { //Requires a value to be returned, class does not need to be initialized for this method to be used. } EXAMPLE public static void WelcomeUser() { Console.WriteLine("Hello Guest!"); } Passing Parameters public static void WelcomeUser(string Name) { Console.WriteLine("Hello " + Name + "!"); } Since both methods have the same name and different parameters (One takes no parameters and the other one does) this is said to be an overloaded method. Returning Data public static DateTime Tomorrow() { return DateTime.Now.AddDays(1); } All the examples above are static, this allows me to use the methods without initializing the class. You can read more about CLASSES SYNTAX Class MyClassName { } EXAMPLE class MyCar { public void Manufacturer(string Manf) { Console.WriteLine(Manf); } } To use the method in the class, the class must be initialized first. MyCar NewCar = new MyCar(); NewCar.Manufacturer("Audi"); If the method was declared static I could simply do this: MyCar.Manufacturer(“Audi”); Static methods are useful, make sure you are using the right design for your classes and methods. A good example is the Math class, to perform simple calculations you do not want to be initializing the class all the time, that’s why most methods are static.