<cat>Dev.Intro</cat> <title>From Lua to C#</title> # What is this guide This is meant to give an idea of the major differences between Lua and C#. # Comments ```lua -- Lua comments start with two minus signs --[[ Lua multiline comment example --]] ``` ```csharp // C# comments start with two slashes, like most other languages /* C# multiline comment example */ ``` # Global Variables ```lua -- you can define globals anywhere in Lua globalVar = 100 ``` ```csharp public class MyClass { // in C# globals need to be in a class public static int GlobalVar = 100; } ``` # Variable Types ```lua -- variables in Lua don't have a static type and can store any data local a = 100 a = "Hello" a = function() print( "Hi" ) end ``` ```csharp var a = 100; // translated as "int a = 100;" because 100 is an int a = "Hello"; // error: can't assign a string to an int ``` # Type conversion ```lua local a = 123 local b = tostring( a ) -- "123" local c = tonumber( b ) -- 123 ``` ```csharp var a = 123; var b = a.ToString(); // "123" var c = int.Parse(b); // 123, will throw an exception if 'b' isn't int-ish // operator 'as' converts an object reference or returns 'null' on failure var vehicle = new Car() as Vehicle; // downcast Car reference to Vehicle var vehicle = vehicle as Car; // upcast Vehicle reference to Car ``` # Numbers ```lua local a = 100 a = 5.5 a = -300.1 ``` ```csharp // integer types are sbyte, byte, short, ushort, int, uint, long, ulong int a = -300; uint b = 333333; // decimal types are float, double, decimal double d = -500.888; ``` # Strings ```lua local str = "Hello" local str2 = 'Hello2' local multilineStr = [[ Hello Multiline ]] print(#str) -- 5, string length local concated = "I have " .. 3 .. " apples!" local formatted = string.format( "I have %d apples!", 3 ) ``` ```csharp var str = "Hello"; var singleChar = 'a'; // single quotes are for a single character, not a string var multilineStr = @" Hello Multiline "; // putting '@' before a string literal makes it a verbatim string literal Console.WriteLine(str.Length); // 5, string length var concated = "I have " + 3 + " apples!"; // {0} and {1} here correspond to the order of value arguments // argument number 0 is '3' and argument number 1 is '2' var formatted = string.Format("I have {0} apples and {1} oranges!", 3, 2); // putting '$' before a string allows interpolating values into it using '{value}' var interpolated = $"I have {3} apples!"; ``` # Collections ```lua local stuff = { 1, 2, 3, "Oh", "Hi", "Mark", { myFunc = function() end } } ``` ```csharp var numbers = new int[3] { 1, 2, 3 }; var strings = new List<string> { "Oh", "Hi", "Mark" }; var functions = new Dictionary<string, Action>⤶ var functions = new Dictionary<string, Func<string, string>> // First type in Func<> is a argument type, Second type is a return type⤶ { ["myFunc"] = () => { } ["myFunc"] = (string strs) => { return strs; } }; ``` # Member Access In Lua anything is accessible from anywhere as long as you have a reference. ```lua -- myFile.lua myTable = { field = 100 } ``` ```lua -- otherFile.lua print( myTable.field ) -- 100 ``` In C# things can be **public**, **private**, **protected** and **internal**. ```csharp // MyClass.cs public class MyClass { public static void PublicMethod() { ... } protected static void ProtectedMethod() { ... } private static void PrivateMethod() { ... } } ``` ```csharp // OtherClass.cs public class OtherClass : MyClass { public static void Test() { MyClass.PublicMethod(); // OK MyClass.ProtectedMethod(); // we inherit from MyClass so OK MyClass.PrivateMethod(); // error: PrivateMethod is private } } ```