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Lua / C# Comparison

Lua / C# Comparison

Aug 29 2019, 9:18 AM PST 5 min

This article is a general overview of the Lua programming language and how its syntax compares to C#.

General Differences

Comments

Lua

-- Single line comment

--[[
	Block comment
--]]

C#

// Single line comment

/*
	Block comment
*/

Strings

Lua

-- Multi-line string
[[This is a string that,
when printed, will appear
on multiple lines]]
-- Concatenation
s1 = "This is a string "
s2 = "made with two parts."
endString = s1 .. s2

C#

// Multi-line string
"This is a string that,\nwhen printed, will appear\n on multiple lines."
// Concatenation
string s1 = "This is a string ";
string s2 = "made with two parts.";
string endString = s1 + s2;

Conditional Operators

Lua C#
Equal To == ==
Greater Than > >
Less Than < <
Greater Than or Equal To >= >=
Less Than or Equal To <= <=
Not Equal To ~= !=
And and &&
Or or ||

Arithmetic Operators

Lua C#
Addition + +
Subtraction - -
Multiplication * *
Division / /
Modulus % %
Exponentiation ^ **

Reserved Keywords

Below are Lua’s reserved keywords mapped to their C# equivalent. Not all C# keywords are shown.

Lua C#
and
break break
do do
if if
else else
elseif else if
then
end
true true
false false
for for / foreach
function
in in
local
nil null
not
or
repeat
return return
until
while while

Line Endings

Semicolons are not required in Lua, but they will work if used in your code.

Scoping

In Lua, variables and logic can be written in a tighter scope than their function or class by nesting the logic within do and end keywords, similar to nesting it within curly brackets {} in C#. For more details on scope in Lua, please see the /articles/Scope|Scope article.

Lua

local example = "Example text"

do
	example = example .. " changed!"
	print(example)  -- Outputs 'Example text changed!'
end

print(example)  -- Outputs 'Example text'

C#

string example = "Example text";

{
	example += " changed!";
	Console.WriteLine(example);  // Outputs 'Example text changed!'
}

Console.WriteLine(example);  // Outputs 'Example text'

Variables

In Lua, variables do not specify their type when being declared/defined. Also, Lua variables do not have access modifiers, although you may prefix “private” variables with an underscore for readability.

Lua

local variableName = "value"
-- "Public" declaration
local variableName

-- "Private" declaration
local _variableName

C#

string variableName = "value";
// Public declaration
public string variableName

// Private declaration
string variableName;

Loops

For Loops

Lua

-- Forward loop
for i = 1, 10 do
	doSomething()
end
-- Reverse loop
for i = 10, 1, -1 do
	doSomething()
end

C#

// Forward loop
for (int i = 1; i <= 10; i++) {
	doSomething();
}
// Reverse loop
for (int i = 10; i >= 1; i--) {
	doSomething();
}

While Loops

Lua

while boolExpression do
	doSomething()
end
repeat
	doSomething()
until not boolExpression

C#

while (boolExpression) {
	doSomething();
}
do {
	doSomething();
} while (boolExpression)

For Each Loops

Lua

local abcList = {"a", "b", "c"}

for i, v in ipairs(abcList) do
	print(v)
end
local abcDictionary = { a=1, b=2, c=3 }

for k, v in pairs(abcDictionary) do
	print(k, v)
end

C#

List abcList = new List{"a", "b", "c"};

foreach (string v in abcList) {
	Console.WriteLine(v);
}
Dictionary abcDictionary = new Dictionary
{ {"a", 1}, {"b", 2}, {"c", 3} };

foreach (KeyValuePair entry in abcDictionary) {
	Console.WriteLine(entry.Key + " " + entry.Value);
}

Conditional Statements

Lua

-- One condition
if boolExpression then
	doSomething()
end

-- Multiple conditions
if not boolExpression then
	doSomething()
elseif otherBoolExpression then
	doSomething()
else
	doSomething()
end

C#

// One condition
if (boolExpression) {
	doSomething();
}

// Multiple conditions
if (!boolExpression) {
	doSomething();
}
else if (otherBoolExpression) {
	doSomething();
}
else {
	doSomething();
}

Ternary Operations

Lua does not offer a direct equivalent to the C ternary operator a?b:c. However, the Lua idiom (a and b) or c offers a close approximation, provided b is not false.

Lua

local max = (x>y and x) or y

C#

int max = (x>y) ? x: y;

Functions

Be sure to read our article on articles/Understanding Functions in Roblox|Functions to get a deeper understanding of Lua functions.

Generic Functions

Lua

-- Generic function
local function increment(number)
	return number + 1
end

C#

// Generic function
int increment(int number) {
	return number + 1;
}

Variable Argument Number

Lua

-- Variable argument number
local function variableArguments(...)
	print(...)
end

C#

// Variable argument number
void variableArguments(params string[] inventoryItems) {
	for (item in inventoryItems) {
		Console.WriteLine(item);
	}
}

Named Arguments

Lua

-- Named arguments
local function namedArguments(args)
	return args.name .. "'s birthday: " .. args.dob
end

namedArguments{name="Bob", dob="4/1/2000"}

C#

// Named arguments
string namedArguments(string name, string dob) {
	return name + "'s birthday: " + dob;
}

namedArguments(name: "Bob", dob: "4/1/2000");

Try/Catch Structures

Lua

local function fireWeapon()
	if not weaponEquipped then
		error("No weapon equipped!")
	end
	-- Proceed...
end

local success, errorMessage = pcall(fireWeapon)
if not success then
	print(errorMessage)
end

C#

void fireWeapon() {
	if (!weaponEquipped) {
		// Use a user-defined exception
		throw new InvalidWeaponException("No weapon equipped!");
	}
	// Proceed...
}

try {
	fireWeapon();
} catch (InvalidWeaponException ex) {
	// An error was raised
}

Tables

Be sure to read the articles/Table|Tables article to get a deeper understanding on how you can use tables in Lua.

Dictionary Tables

Tables in Lua can be used just like Dictionaries in C#.

Lua

local dictionary = {
	val1 = "this",
	val2 = "is"
}

print(dictionary.val1)  -- Outputs 'this'
print(dictionary[val1])  -- Outputs 'this'

dictionary.val1 = nil  -- Removes 'val1' from table
table.remove(dictionary, 1)  -- Also removes 'val1' from table

dictionary["val3"] = "a dictionary"  -- Overwrites 'val3' or sets new key-value pair

C#

Dictionary dictionary = new Dictionary()
{
	{ "val1", "this" },
	{ "val2", "is" }
};

Console.WriteLine(dictionary["val1"]);  // Outputs 'this'

dictionary.Remove("val1");  // Removes 'val1' from dictionary

dictionary["val3"] = "a dictionary";  // Overwrites 'val3' or sets new key-value pair
dictionary.Add("val3", "a dictionary");  // Creates a new key-value pair

Numerically-Indexed Tables

Tables in Lua can also be used like a List in C#. The key difference is that indices start at 1 with Lua and 0 with C#.

Lua

local NPCAttributes = {"strong", "intelligent"}

print(NPCAttributes[1])  -- Outputs 'strong'

print(#NPCAttributes)  -- Outputs the size of the list

-- Append to the list
table.insert(NPCAttributes, "humble")
-- Another way...
NPCAttributes[#NPCAttributes+1] = "humble"

-- Insert at the beginning of the list
table.insert(NPCAttributes, 1, "brave")

-- Remove item at a given index
table.remove(NPCAttributes, 3)

C#

List NPCAttributes = new List{"strong", "intelligent"};

Console.WriteLine(NPCAttributes[0]);  // Outputs 'strong'

Console.WriteLine(NPCAttributes.Count);  // Outputs the size of the list

// Append to the list
NPCAttributes.Add("humble");
// Another way...
NPCAttributes.Insert(NPCAttributes.Count, "humble");

// Insert at the beginning of the list
NPCAttributes.Insert(0, "brave");

// Remove item at a given index
NPCAttributes.Remove(2);
Tags:
  • lua
  • c#
  • syntax
  • code