<cat>Code.Misc</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#. This is meant to give an idea of some major differences between Lua and C#. ⤶ This isn't a complete guide to C# and it doesn't cover many of the topics. It's meant to be brief, simple and illustrative. If you want to learn C# in more depth, you can use the [official C# language reference](https://docs.microsoft.com/en-us/dotnet/csharp/).⤶ # 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 car = 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 } } ⤶ local arr = { 'a', 'b', 'c' }⤶ ⤶ print( arr[1] ) -- will print 'a' since array indices in Lua start from 1⤶ ``` ```csharp var numbers = new int[3] { 1, 2, 3 }; var strings = new List<string> { "Oh", "Hi", "Mark" }; var functions = new Dictionary<string, Action> { ["myFunc"] = () => { } }; ⤶ var arr = new string[3] { "a", "b", "c" };⤶ ⤶ Console.WriteLine(arr[1]); // will print "b" since array indices in C# like most languages start from 0⤶ ``` # Loops ```lua for i = 1, 10, 2 do print( i ) -- 1, 3, 5, 7, 9 end local a = 10 repeat print( a ) -- 10, 8, 6, 4, 2, 0 a = a - 2 until a < 0 local t = { a = 5, b = 10, c = 15 } for k, v in pairs( t ) do print( k .. ' = ' .. v ) -- b = 10, a = 5, c = 15 end ``` ```csharp for ( var i = 1; i < 10; i += 2 ) { Console.WriteLine( i ); // 1, 3, 5, 7, 9 } var a = 10; do { Console.WriteLine( a ); // 10, 8, 6, 4, 2, 0 a -= 2; } while ( a >= 0 ); var t = new Dictionary<string, int> { { "a", 5 }, { "b", 10 }, { "c", 15 }, }; foreach (var kv in t) { Console.WriteLine( $"{kv.Key} = {kv.Value}" ); //a = 5, b = 10, c = 15 } ``` # 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 } } ```