Simple Lua (New)

Old version

Printing

So you've decided to start programming in a little lua?

First thing you should know how to print lines in lua, otherwise it will be harder to debug your programs.

Function	Info	Arguments
print(string)	prints text on the screen example: print("Best Worlds!")	string = text displayed on screen
write(string)	writes text on the screen but doesn't go to the next line when finished	string = text displayed on screen

Tags: Minecraft lua creating software 

Variables

Now you may be wondering how you are to have a value that you can change in different parts of your program

Well, it's pretty simple as all you really need to do is type your variable name, then a "=", and then assign the variable to a string or integer value, like so:

var0 = "Put whatever you want here!"

var1 = 12345

Note that if you have a string assigned to variable, you MUST surround it with quotes.  You don't however, need quotes around a number.

Functions

A function is a piece of code that can be called over again after it's been made. Here's an example of a function:

function abc()
    --Enter your code here to make the function
end

Functions can also have variables and look like this:

function abc(d,e,f,g,h)
    --Enter your code here to make a function
end

You can also assign functions to variables like so:

abc = function(d,e,f,g,h)
    --Enter your code here to make the function
end

Functions are useful when you are going to use a series of commands several times, and you don't want to constantly retype the same chunk of code.  For example, if I wanted to make a turtle turn around, then move up, then down, then turn back around, and do it all twice, I could write:

turtle.turnLeft()
turtle.turnLeft()
turtle.up()
turtle.down()
turtle.turnRight()
turtle.turnRight()
turtle.turnLeft()
turtle.turnLeft()
turtle.up()
turtle.down()
turtle.turnRight()
turtle.turnRight()
end

OR you can do this:

function dance()

    turtle.turnLeft()
    turtle.turnLeft()
    turtle.up()
    turtle.down()
    turtle.turnRight()
    turtle.turnRight()

end

dance()
dance()

See how the second option is a lot shorter?  This was a basic example, but the prinicple remains.

[EXTRA EDIT] A shorter still example is right here:

for i = 1, 2, 1 do
    turtle.turnLeft()
    turtle.turnLeft()
    turtle.up()
    turtle.down()
    turtle.turnRight()
    turtle.turnRight()
end

Logic and loops

Logic is the core aspect of computers, and will be used in virtually all of your programs.

Let's say you want something to execute another piece of code if it's true,

You would use an IF statement which basically is where if the statement is true it'll execute the code between the "if" statement and the "end" break

An if statement compared to a real life statement

Real Life	In Lua
If you want to go to the park then let's go to the park.	if wantsToGoToPark==true then goToPark() end

So you see that it's very easy to remember how to do an if statement. You can also simplify this by removing the "== true" as the if statement checks only if the condition (wantsToGoToPark==true) evaluates to true.

Now you may be wondering how you'd write out a mathematical equation, that's simple you just write it out as you normally would, for example;

Greater than

if x>3 then 

-- Code goes here

end

Less than

if x<3 then 

-- C

end

e

end

end

nd

end

reater han o

qual to

if x>=3 then 

-- Code goes here

end

Less than or equal to

if x<=3 then 

-- Code goes here

end

However if ,for example, you want to get "true" when the statement is "false", you'd do something like this:

if x~=3 then 

-- Code goes here

end

Now you may be wondering how to do both sides without rewriting the entire code.  To do so, just use an "else" statement like so:

if x>3 then 
-- Code goes here
else
-- Code goes here
end

Gates

If you know how to write domains like this: x>4 OR x<6 then you pretty much know how to do an "OR" gate already, for example:

if x>4 or x<6 then
-- Code goes here
end

Be careful! If the condition on the first side is true, the other side isn't checked unless the first equation is false. For example:

x = 6
if x>5 or x<10 then --The right side of the equation isn't checked because x>5 is true
-- Code goes here
end

An "AND" gate is similar, it's just that both logics have to result in true:

if x>4 and x<6 then
-- Code goes here
end

if v1 == v2 and v3 ~= v4 then
-- Code goes here
end

If you want to do something if the condition is met and something else is not then you must add an else clause

if v1 == v2 then
-- Code goes here
else
-- Code goes here
end

But what if you want 3 or more possibilities? Then you need to use the elseif clause. The elseif clause is only executed on certain conditions. For example;

if v1 == v2 then

    --code

elseif v1 > v2 then --But if not, check if this inequality/equation is true. Then do this.

    --code

else --But if not, do this.

    --code

end

So when are we learning about Loops? Well there are 2 mainly used loops:

while loops and for loops

A while loop is a special kind of loop that repeats until its condition is met. So if you want an infinite loop, use this while loop:

while true do --This is an infinite loop, it never stops!
--Code
end

But if you want a loop that stops on a certain condition:

con = 5
met = 0

    while met < con do
    met = met+ 1
    sleep(1)
    print met

end

If you want to read a players action like for a password, you would use the "read" function like so:

write "Enter Password: " -- this displays "Enter Password: "(and reads only past here)

password = read() -- allows an Input into the variable named "password", which is a string