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Operators

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In this section, we will explore the various operators available in Lua. Operators are special symbols or keywords that are used to perform operations on variables and values. Lua supports several types of operators, including arithmetic, relational, logical, and more.

Types of Operators

  1. Arithmetic Operators
  2. Relational Operators
  3. Logical Operators
  4. Concatenation Operator
  5. Length Operator
  6. Miscellaneous Operators

  1. Arithmetic Operators

Arithmetic operators are used to perform basic mathematical operations. Here are the arithmetic operators available in Lua:

Operator Description Example
+ Addition a + b
- Subtraction a - b
* Multiplication a * b
/ Division a / b
% Modulus (Remainder) a % b
^ Exponentiation a ^ b
- Unary Negation -a

Example:

local a = 10
local b = 3

print("Addition: ", a + b)        -- Output: 13
print("Subtraction: ", a - b)     -- Output: 7
print("Multiplication: ", a * b)  -- Output: 30
print("Division: ", a / b)        -- Output: 3.3333333333333
print("Modulus: ", a % b)         -- Output: 1
print("Exponentiation: ", a ^ b)  -- Output: 1000
print("Unary Negation: ", -a)     -- Output: -10

  1. Relational Operators

Relational operators are used to compare two values. They return true or false based on the comparison.

Operator Description Example
== Equal to a == b
~= Not equal to a ~= b
> Greater than a > b
< Less than a < b
>= Greater than or equal to a >= b
<= Less than or equal to a <= b

Example:

local a = 10
local b = 3

print("Equal to: ", a == b)       -- Output: false
print("Not equal to: ", a ~= b)   -- Output: true
print("Greater than: ", a > b)    -- Output: true
print("Less than: ", a < b)       -- Output: false
print("Greater than or equal to: ", a >= b) -- Output: true
print("Less than or equal to: ", a <= b)    -- Output: false

  1. Logical Operators

Logical operators are used to combine multiple conditions.

Operator Description Example
and Logical AND a and b
or Logical OR a or b
not Logical NOT not a

Example:

local a = true
local b = false

print("Logical AND: ", a and b)   -- Output: false
print("Logical OR: ", a or b)     -- Output: true
print("Logical NOT: ", not a)     -- Output: false

  1. Concatenation Operator

The concatenation operator (..) is used to join two strings together.

Example:

local str1 = "Hello"
local str2 = "World"

print("Concatenation: ", str1 .. " " .. str2) -- Output: Hello World

  1. Length Operator

The length operator (#) is used to get the length of a string or the number of elements in a table.

Example:

local str = "Hello"
local tbl = {1, 2, 3, 4, 5}

print("Length of string: ", #str) -- Output: 5
print("Length of table: ", #tbl)  -- Output: 5

  1. Miscellaneous Operators

Lua also supports some miscellaneous operators like the assignment operator (=) and the table access operator (.).

Example:

local tbl = {name = "Lua"}

-- Assignment
tbl.age = 30

-- Table access
print("Name: ", tbl.name) -- Output: Lua
print("Age: ", tbl.age)   -- Output: 30

Practical Exercises

Exercise 1: Basic Arithmetic Operations

Write a Lua script that takes two numbers as input and performs all the arithmetic operations on them.

Solution:

local a = 15
local b = 4

print("Addition: ", a + b)
print("Subtraction: ", a - b)
print("Multiplication: ", a * b)
print("Division: ", a / b)
print("Modulus: ", a % b)
print("Exponentiation: ", a ^ b)

Exercise 2: Relational and Logical Operations

Write a Lua script that compares two numbers and prints the results of various relational and logical operations.

Solution:

local a = 7
local b = 10

print("Equal to: ", a == b)
print("Not equal to: ", a ~= b)
print("Greater than: ", a > b)
print("Less than: ", a < b)
print("Greater than or equal to: ", a >= b)
print("Less than or equal to: ", a <= b)

local x = true
local y = false

print("Logical AND: ", x and y)
print("Logical OR: ", x or y)
print("Logical NOT: ", not x)

Exercise 3: String Concatenation

Write a Lua script that concatenates three strings and prints the result.

Solution:

local str1 = "Lua"
local str2 = "is"
local str3 = "awesome"

print("Concatenation: ", str1 .. " " .. str2 .. " " .. str3)

Conclusion

In this section, we covered the various operators available in Lua, including arithmetic, relational, logical, concatenation, and length operators. We also provided practical examples and exercises to help reinforce the concepts. Understanding these operators is crucial for performing operations on data and controlling the flow of your Lua programs. In the next section, we will delve into control structures, which will allow you to make decisions and control the execution flow of your scripts.

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