Lua Cheatsheet

Sample program

name = io.read("*a")
print ("Hello ", name)

• io.read : to read the data from console

• print : to output the data to console.

• -- : comment

• --[[ Multi

  Line

  comments --]]

Variables

• Lua is a dynamically typed language and hence only the values will have types not the variables.

Examples

-- global variables, variables are by default global
x = 10

-- local variables

local x = 30

Data types

Value Type	Description
number	Represents numbers
string	Represents text
nil	Differentiates values whether it has data or not
boolean	Value can be either true or false
function	Represents a sub-routine
userdata	Represents arbitary C data
thread	Represents independent threads of execution.
table	Can hold any value except nil

Operators

Operator type	Description
Arithmetic Operator	+ , - , * , / , %, -
comparision Operator	< , > , <= , >=, ~=, ==
Logical Operator	and , or, not
Misc Operator	.. , #

There are no ++, --, ternary operators in lua

String methods

Method	Description
str1 .. str2	String concatenation
string.len(str)	To get the length of a string
string.gsub(str, "t1", "t2")	Used to Replace t1 with t2 in the string str
string.find(str, txt)	Searches for txt in str string and returns it's index
string.upper(str)	to change the str to upper case
string.lower(str)	to change the str to lower case

Conditional statements

1. If

if conditional-expression then
--code
end

2. If-else

if conditional-expression then
   --code
elseif conditional-expression then
    --code
else
    --code
end

There is no switch in Lua

Loops

1. While

while(condition)
do
--code
end

2. Repeat-Until

repeat
   --code
until( condition )

3. For

for init,max/min value, increment
do
   --code
end

Functions

[function_scope] function function_name( argument1, argument2, argument3........, argumentn)
--code
return params with comma seperated
end

Example

function sum(x,y)
	sum=x+y
	return sum
end

print(sum(10,20))