编辑“︁StendhalScripting/Lua”︁（章节）

== Data Types ==

Some common data types in Lua are ''string'', ''integer'', ''boolean'', & ''table''. Type names do not need to be declared when setting variables.

Examples:
<pre>
-- string variable
local var1 = "Hello world!"

-- integer variable
local var2 = 11

-- boolean variable
local var3 = true

-- table variable
local var4 = {}
</pre>

=== Strings ===

==== String Concatenation ====

String concatenation is simple, much like Java uses a plus operator (<code>+</code>) to join strings, Lua uses two periods (<code>..</code>).

Example:
<pre>
-- create a string variable
local var = "Hello"

-- append another string
var = var .. " world!"

print(var) -- prints "Hello world!"
</pre>

=== Tables ===

A Lua table is a data type similar to a Java list or map. Tables can be indexed or use key=value pairs.

''(<span style="color:red;">IMPORTANT NOTE: Lua table indexes begin at 1, not 0</span>)''

==== Creating Tables ====

An empty table is initialized with a pair of curly braces (<code>{}</code>):
<pre>
local mytable = {}
</pre>

You can add values to indexed tables at initialization or with the <code>table.insert</code> method:
<pre>
-- create a table with values
local mytable = {"foo"}

-- add value
table.insert(mytable, "bar")
</pre>

To create a key=value table, any of the following methods can be used to add values:
<pre>
-- all of these do the same thing, that is, assigning "bar" to mytable.foo
local mytable {
	foo = "bar",
	["foo"] = "bar",
}
mytable.foo = "bar"
mytable["foo"] = "bar"
</pre>

==== Accessing Table Values ====

Square brackets (<code>[]</code>) enclosing an index number are used to access values in indexed tables (''remember that Lua table indexes start at "1" not "0"''):
<pre>
local mytable = {"foo", "bar"}

print(mytable[1]) -- prints "foo"
print(mytable[2]) -- prints "bar"
</pre>

In a key=value table, values can be accessed by either enclosing the key string in square brackets or concatenating the key member using a <code>.</code>:
<pre>
local mytable = {foo="bar"}

-- using square brackets
print(mytable["foo"]) -- prints "bar"

-- using concatenated member
print(mytable.foo) -- prints "bar"
</pre>

==== Iterating Tables ====

Tables can be iterated in a <code>for</code> loop using the <code>pairs</code> or <code>ipairs</code> iterators. Loops are terminated with the <code>end</code> keyword:
<pre>
local mytable = {"foo", "bar"}

print("indexes:")
for idx in pairs(mytable) do
	print(idx)
end

print("\nvalues:")
for idx, value in pairs(mytable) do
	print(value)
end
</pre>

Output:
<pre>
indexes:
1
2

values:
foo
bar
</pre>

Using a key=value table:
<pre>
local mytable = {
	["foo"] = "hello",
	["bar"] = " world!",
}

print("keys:")
for key in pairs(mytable) do
	print(key)
end

print("\nvalues:")
for key, value in pairs(mytable) do
	print(value)
end
</pre>

Output:
<pre>
keys:
foo
bar

values:
hello
 world!
</pre>

See also: [http://lua-users.org/wiki/TablesTutorial Lua Tables Tutorial]

=== Functions ===

Like normal variables, functions can be declared as '''global''' or '''local''' & must be terminated with the <code>end</code> keyword.

There are two ways to define functions with the <code>function</code> keyword:
<pre>
local function myFunction()
	print("Hello world!")
end
</pre>

or
<pre>
local myFunction = function()
	print("Hello world!")
end
</pre>

Functions can also be members of a table:
<pre>
local myTable = {}
function myTable.myFunction()
	print("Hello world!")
end
</pre>

or
<pre>
local myTable = {}
myTable.myFunction = function()
	print("Hello world!")
end
</pre>

or
<pre>
local myTable = {
	myFunction = function()
		print("Hello world!")
	end,
}

-- execute with
myTable.myFunction()
</pre>