An Introduction To Lua Programming Language

1. Lua Programming
Language

2. Agenda
• Introduction to Lua
• Data Types in Lua
• Reserved Words & Variables
• Operators
• Control Statements
• Functions
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3. Introduction to Lua
What is Lua
and why to use
Lua?

4. What is Lua?
• Lua is a powerful, efficient,
lightweight, embeddable scripting
language. It supports procedural
programming, OOP, functional
programming, data driven
programming etc.
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5. Advantages of Lua
Powerful Fast
• Lua is a very beginner friendly language and
is easy to implement.
• Lua is not a pure object-oriented language,
yet it provide meta-mechanisms for
implementing classes and other OOP
concepts.
• Lua has a safe environment, automatic
memory management, and good facilities for
handling strings and other kinds of data with
dynamic size.
• Lua has a deserved reputation for
performance.
• To claim to be ‘as fast as Lua’ is an
aspiration of other scripting
languages.
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6. Advantages of Lua
Portable Embeddable
Lua runs on:
• All flavors of Unix
• Windows
• On mobile devices (running Android,
iOS, Windows Phone)
• Embedded microprocessors (ARM and
Rabbit) and even on IBM mainframes.
• Lua has a simple and well documented
API that allows strong integration with
code written in other languages.
• C, C++, C#, Java, Perl, Ruby
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7. Data Types in Lua Data types
available in Lua

8. Data Types
• Lua is a dynamically typed language.
• There are no type definitions in the language; each value carries its own type.
• Values ​​can be stored in variables, passed as a parameter or return the results.
• Lua has eight basic types are: nil, Boolean, number, string, userdata, function, thread
and table.
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9. Example
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10. Data Types in Lua
nil as a kind of non-value, to represent the absence of a useful value (equivalent to false in conditional expressions).
nil
The Boolean type has two values, false and true.
Boolean
The number type represents real (double-precision floating-point) numbers.
Number
Strings have the usual meaning: a sequence of characters.
String
The table type implements associative arrays, the index of the array can be a number or a string.
Tables
Functions can be stored in variables, passed as arguments to other functions, and returned as results.
Functions
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11. Tables
• The table type implements associative arrays.
• An associative array is an array that can be indexed not only
with numbers, but also with strings or any other value of the
language, except nil.
• Moreover, tables have no fixed size; you can add as many
elements as you want to a table dynamically.
• Also, you can assign nil to a table field to delete it.
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12. Tables
• To create a table a table constructor expression is used.
• In its simplest form it is written as {}.
• To access elements of a table [] is used.
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13. Nested Tables
• It is possible to implement nested tables in Lua.
• To do so simply assign tables as the elements of another
table.
• To access the tables inside tables [][] is used.
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14. Example
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15. Table Manipulation
• Insertion and removal of items in tables is most common in
table manipulation.
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Inserts a value into the table at specified position.
table.insert
(table, pos,
value)
Removes the value from the table.
table.remove
(table , pos)

16. Example
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17. Reserved Words &
Variables
Variable
naming and
reserved words

18. Variable names or Identifiers
Identifiers in Lua can be any string of letters, digits, and
underscores, not beginning with a digit or other special
characters; for instance:
i player MAX_health
_ij aVeryLongname _INPUT
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19. Global Variables
• Global variables do not need declarations. You simply assign
a value to a global variable to create it.
• It is not an error to access a non-initialized variable; you just
get the special value nil as the result.
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20. Global Variables
• Usually, you do not need to delete global variables; if your variable
is going to have a short life, you should use a local variable.
• But, if you need to delete a global variable, just assign nil to it.
• After that, it is as if the variable had never been used. In other
words, a global variable is existent if (and only if) it has a non-nil
value.
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21. Local Variables
• Besides global variables, Lua supports local variables. We
create local variables with the local statement:
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22. Local Variables
• Unlike global variables, local variables have their scope
limited to the block where they are declared.
• A block is the body of a control structure, the body of a
function, or a chunk (the file or string with the code where the
variable is declared).
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23. Example
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24. Reserved Words
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and break do else elseif end false
for function if in local nil not
or repeat return then true until while
The following words are reserved; we cannot use them as
identifiers:

25. Operators
Various
operators and
their use

26. Arithmetic Operators
Consider A=10, B=20:
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27. Relational Operators
Consider A=10, B=20:
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28. Example
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29. Logical Operators
Consider A = a week has 7 days. B = February month can have 31 days.
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30. Example
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31. Control Statements
Control
structures in
Lua

32. Control Structures
• Lua provides a small and conventional set of control
structures, with if for conditional and while and for for
iteration.
• All control structures have an explicit terminator: end
terminates the if, for and while structures.
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33. if then else
• An if statement tests its condition and executes its then-part
or its else-part accordingly. The else-part is optional.
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34. elseif
• When you write nested ifs, you can use elseif. It is similar to
an else followed by an if, but it avoids the need for multiple
ends:
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35. while
• As usual, Lua first tests the while condition; if the condition is
false, then the loop ends; otherwise, Lua executes the body
of the loop and repeats the process.
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36. Numeric for
• The for statement has two variants: the numeric for and the generic for.
• A numeric for has the following syntax:
• That loop will execute something for each value of var from exp1 to
exp2, using exp3 as the step to increment var. This third expression is
optional; when absent, Lua assumes one as the step value.
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for var=exp1,exp2,exp3 do
something
end

37. Example
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38. Generic for
• The generic for in Lua allows us to iterate over the values in
an iterator fashion; it is much more powerful even though it
looks simple.
• The Lua library has plenty of iterators, over which we can use
the generic for loop.
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39. Generic for
• Its syntax is:
• The i in the above syntax denotes the index of the items we are
going to iterate over only by one, and the v denotes the actual
values of those items. The x is the iterable item over which we
are iterating, it can be a table, list, array, or map.
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for i, v in pairs(x) do
...
...
end

40. Example
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41. Functions Syntax and use
of Functions

42. Functions
• Syntax of functions in Lua is:
• In the syntax, a function definition has a name, a list of
parameters, and a body, which is a list of statements.
function function_name (parameters)
..
..
end
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43. Example
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44. Multiple Results
• Functions written in Lua also can return multiple results, by
listing them all after the return keyword.
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