<cat>Code.Misc</cat> <title>From Lua to C#</title> ⤶ <deprecated>[this page](https://wiki.facepunch.com/sbox/Learning_Resources)</deprecated> ⤶ <deprecated>[Read this page instead](https://wiki.facepunch.com/sbox/Learning_Resources)</deprecated> <warning> This page won't teach you how to use C#. In order to effectively use C#, please check out [this page](https://wiki.facepunch.com/sbox/Learning_Resources). </warning> # What is this page 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, please check out [this page](https://wiki.facepunch.com/sbox/Learning_Resources). # Terminology ## Tables Tables do not exist in C#: although they are not exactly a replacement, in most cases you will use *classes* instead. ## Variables In C# only variables defined in methods are called so. If it's defined in a class it is called a *field* instead. Example: ```csharp public class Player { private int _health; // field public void Damage( int amount, int times ) { var totalAmount = amount * times; // variable } } ``` ## Functions In C# they are called *methods* instead. # 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 */ ``` # Typing System Lua uses dynamic typing. That means variables do not have a specific type and can be assigned any type of value. ```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 ``` C# uses static typing. That means a variable has a known type that is set during its declaration. Only compatible values can be assigned. For example, you cannot assign a string value to an int variable. ```csharp int a = 100; a = "Hello"; // error: can't assign a string to an int ``` There are multiple built in data types in C#. You can view all of them [here](https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/builtin-types/built-in-types) You can also use the `var` keyword for the type to be inferred. This is considered bad practice to be used constantly and should only be used when defining explicit types. ```csharp var veh = new Vehicle(); // veh will have the type of Vehicle ``` ## Type Conversion ```lua local a = 123 local b = tostring( a ) -- "123" local c = tonumber( b ) -- 123 ``` ```csharp int a = 123; string b = a.ToString(); // "123" int 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 Vehicle vehicle = new Car() as Vehicle; // downcast Car reference to Vehicle Car car = vehicle as Car; // upcast Vehicle reference to Car ``` # 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 string str = "Hello"; char singleChar = 'a'; // single quotes are for a single character, not a string // While there are many ways to concatenate a string, this is the preferred method. // putting '$' before a string allows interpolating values into it using '{value}' int appleCount = 3; string interpolated = $"I have {appleCount} apples!"; ``` # 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 ( int i = 1; i < 10; i += 2 ) { Console.WriteLine( i ); // 1, 3, 5, 7, 9 } int a = 10; do { Console.WriteLine( a ); // 10, 8, 6, 4, 2, 0 a -= 2; } while ( a >= 0 ); Dictionary<string, int> t = new Dictionary<string, int> { { "a", 5 }, { "b", 10 }, { "c", 15 }, }; foreach ( KeyValuePair<string, int> kv in t ) { Console.WriteLine( $"{kv.Key} = {kv.Value}" ); //a = 5, b = 10, c = 15 } ```