4.18. Lua operator

发布时间 ： 2025-10-25 13:34:08 UTC      

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An operator is a special symbol that tells the interpreter to perform specific mathematical or logical operations. Lua provides the following types of operators:

  • Arithmetic operator

  • Relational operator

  • Logical operator

  • Other operators

4.18.1. Arithmetic operator #

The following table lists the common arithmetic operators in the Lua language, setting A to 10 and B to 20:

Operator

Description

Example

+

Addition

A + B output result 30

-

Subtraction

A-B output result-10

*

Multiplication

A * B output result 200

/

Division

B / A output result 2

%

Take the remainder

B An output result 0

^

Multiplying power

A^2 output result 100

-

Minus sign

-A output result-10

//

Integer division operator (> = lua5.3)

5Compact 2 output result 2

4.18.2. Example #

We can understand the application of arithmetic operators more thoroughly through the following examples:

Example # 

a = 21 b = 10 c = a + b print("The value of Line 1- c is ", c ) c = a - b print("The value of Line 2- c is ", c ) c = a * b print("The value of Line 3- c is ", c ) c = a / b print("The value of Line 4- c is ", c ) c = a % b print("The value of Line 5- c is ", c ) c = a^2 print("The value of Line 6- c is ", c ) c = -a print("The value of Line 7-c is ", c )

The execution results of the above procedures are as follows:

The value of Line 1- c is 31 The value of Line 2- c is 11 The value of Line 3- c is 210 The value of Line 4- c is 2.1 The value of Line 5- c is 1 The value of Line 6- c is 441 The value of Line 7- c is -21

In lua, / is used as a division operation, the result contains the decimal part, // is used as an integral division operation, and the result does notinclude the decimal part:

Example # 

a = 5 b = 2 print("The value of division operation - a/b is ", a / b ) print("The value of integer division - a/b is ", a // b )

The execution results of the above procedures are as follows:

Division operation - the value of a/b is 2.5 The value of integer division - a/b is 2

4.18.3. Relational operator #

The following table lists the common relational operators in the Lua language, setting the value of A to 10 and the value of B to 20:

Operator

Description

Example

==

Equals, checks whether two values are equal, returns true, otherwise returnsfalse

(A == B) is false.

~=

Not equal. Check whether two values are equal. Return true if they are not equal, otherwise return false.

(A ~= B) is true.

>

Greater than, if the value on the left is greater than the value on the right, return true, otherwise return false

(A > B) is false.

<

Less than, if the value on the left is greater than the value on the right, return false, otherwise return true

(A < B) is true.

>=

Greater than or equal to, if the value on the left is greater than or equal to the value on the right, return true, otherwise return false

(A >= B) returns false.

<=

Less than or equal to, if the value on the left is less than or equal to thevalue on the right, return true, otherwise return false

(A <= B) returns true.

4.18.4. Example #

We can understand the application of relational operators more thoroughly through the following examples:

Example # 

a = 21 b = 10 if( a == b ) then print("Line 1 - a = b" ) else print("Line 1 - a ≠ b" ) end if( a ~= b ) then print("Line 2 - a ≠ b" ) else print("Line 2 - a = b" ) end if ( a < b ) then print("Line 3 - a < b" ) else print("Line 3 - a ≥ b" ) end if ( a > b ) then print("Line 4 - a > b" ) else print("Line 5 - a ≤ b" ) end -- Modify the values of a and b a = 5 b = 20 if ( a <= b ) then print("Line 5 - a ≤ b" ) end if ( b >= a ) then print("Line 6 - b ≥ a" ) end

The execution results of the above procedures are as follows:

Line 1 - a ≠ b Line 2 - a ≠ b Line 3 - a ≥ b Line 4 - a > b Line 5 - a ≤ b Line 6 - b ≥ a

4.18.5. Logical operator #

The following table lists the common logical operators in the Lua language, setting the value of A to true , the value of B is false :

Operator

Description

Example

and

Logic and operators. If A is false, return A, otherwise return B.

(A and B) is false.

or

Logic or operator. If A is true, return A, otherwise return B.

(A or B) is true.

not

Logical non-operator. Contrary to the logic operation result, if the condition is true, the logic is not false.

not (A and B) is true.

4.18.6. Example #

We can understand the application of logical operators more thoroughly through the following examples:

Example # 

a = true b = true if ( a and b ) then print("a and b - Condition is true" ) end if ( a or b ) then print("a or b - Condition is true" ) end print("---------Divider---------" ) -- Modify the values of a and b a = false b = true if ( a and b ) then print("a and b - Condition is true" ) else print("a and b - Condition is false" ) end if ( not( a and b) ) then print("not( a and b) - Condition is true" ) else print("not( a and b) - Condition is false" ) end

The execution results of the above procedures are as follows:

a and b - Condition is true a or b - Condition is true ---------Divider--------- a and b - Condition is false not( a and b) - Condition is true

4.18.7. Other operators #

The following table lists the concatenation operators in the Lua language and operators that calculate the length of a table or string:

Operator

Description

Example

Concatenate two strings

a..b, where an is “Hello”, b is “World”, and the output is “Hello World”.

#

Unary operator that returns the length of a string or table.

#”Hello” returns 5

4.18.8. Example #

We can better understand the application of concatenation operators and operators that calculate the length of tables or strings through the following examples:

Example # 

a = "Hello " b = "World" print("Connection strings a and b ", a..b ) print("B String length ",#b ) print("String Test Length ",#"Test" ) print("Newbie tutorial website length ",#"www.runoob.com" )

The execution results of the above procedures are as follows:

Connection strings a and b Hello World B String length 5 String Test Length 4 Newbie tutorial website length 14

4.18.9. Operator precedence #

The order from high to low:

^ not - (unary) * / % + - .. < > <= >= ~= == and or

Except ^ and .. all binary operators outside are left concatenated.

a+i < b/2+1 <--> (a+i) < ((b/2)+1) 5+x^2*8 <--> 5+((x^2)*8) a < y and y <= z <--> (a < y) and (y <= z) -x^2 <--> -(x^2) x^y^z <--> x^(y^z)     
 
  4.18.10.  Example  #  
 
 We can get a more thorough understanding of the precedence of Lua language operators through the following examples: 
 
 
 Example  #  
 
 
 
a = 20 b = 10 c = 15 d = 5 e = (a + b) * c / d;-- ( 30 * 15 ) / 5 print("(a + b) * c / d operation value is :",e ) e = ((a + b) * c) / d; -- (30 * 15 ) / 5 print("((a + b) * c) / d operation value is :",e ) e = (a + b) * (c / d);-- (30) * (15/5) print("(a + b) * (c / d) operation value is :",e ) e = a + (b * c) / d; -- 20 + (150/5) print("a + (b * c) / d operation value is :",e ) 
 
 
 
 The execution results of the above procedures are as follows: 
 
 
 
(a + b) * c / d operation value is : 90.0 ((a + b) * c) / d operation value is : 90.0 (a + b) * (c / d) operation value is : 90.0 a + (b * c) / d operation value is : 50.0 
 
 
 
 
  
                
                

                    

                        

                            
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