Lua operators

The

operator is a special symbol used to tell the interpreter to perform a specific mathematical or logical operation. Lua provides the following operator types:

Arithmetic operators
Relational operators
Logical operators
Other operators

Arithmetic operators

The following table lists Lua Commonly used arithmetic operators in the language, set the value of A to 10 and the value of B to 20:

##*MultiplicationA * B Output result 200 /DivisionB / A wOutput result 2%RemainderB % A Output result 0^Multiply powerA^2 Output result 100-negative sign-A output result v -10

Operator	Description	Example
+	Addition	A + B Output result 30
-	Subtraction	A - B Output result-10

Example

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

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

The execution result of the above program is:

Line 1 - c 的值为 	31
Line 2 - c 的值为 	11
Line 3 - c 的值为 	210
Line 4 - c 的值为 	2.1
Line 5 - c 的值为 	1
Line 6 - c 的值为 	441
Line 7 - c 的值为 	-21

Relational operator

The following table lists the commonly used relational operators in Lua language. Set the value of A to 10 and the value of B to 20:

##Operator==~=><>=<=

Examples

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

a = 21
b = 10

if( a == b )
then
   print("Line 1 - a 等于 b" )
else
   print("Line 1 - a 不等于 b" )
end

if( a ~= b )
then
   print("Line 2 - a 不等于 b" )
else
   print("Line 2 - a 等于 b" )
end

if ( a < b )
then
   print("Line 3 - a 小于 b" )
else
   print("Line 3 - a 大于等于 b" )
end

if ( a > b ) 
then
   print("Line 4 - a 大于 b" )
else
   print("Line 5 - a 小于等于 b" )
end

-- 修改 a 和 b 的值
a = 5
b = 20
if ( a <= b ) 
then
   print("Line 5 - a 小于等于  b" )
end

if ( b >= a ) 
then
   print("Line 6 - b 大于等于 a" )
end

The execution result of the above program is:

Line 1 - a 不等于 b
Line 2 - a 不等于 b
Line 3 - a 大于等于 b
Line 4 - a 大于 b
Line 5 - a 小于等于  b
Line 6 - b 大于等于 a

Logic Operators

The following table lists the commonly used logical operators in Lua language. Set the value of A to true and the value of B to false:

Description	Instance
Equal, detect whether two values are equal, return true if equal, otherwise return false	(A == B) is false.
is not equal, checks whether the two values are equal, returns false if equal, otherwise returns true<	(A ~= B) is true.
is 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 the value on the right, return true, otherwise return false	(A < = B) returns true.

Operator	Description	Instance
and	Logical AND operator. The condition is true if both operations are true.	(A and B) is false.
or	Logical OR operator. The condition is true if either operation on both sides is true.	(A or B) is true.
not	Logical NOT operator. Contrary to the result of a logical operation, if the condition is true, logical negation is false.	not(A and B) is true.

Examples

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

a = true
b = true

if ( a and b )
then
   print("a and b - 条件为 true" )
end

if ( a or b )
then
   print("a or b - 条件为 true" )
end

print("---------分割线---------" )

-- 修改 a 和 b 的值
a = false
b = true

if ( a and b )
then
   print("a and b - 条件为 true" )
else
   print("a and b - 条件为 false" )
end

if ( not( a and b) )
then
   print("not( a and b) - 条件为 true" )
else
   print("not( a and b) - 条件为 false" )
end

The execution result of the above program is ：

a and b - 条件为 true
a or b - 条件为 true
---------分割线---------
a and b - 条件为 false
not( a and b) - 条件为 true

Other operators

The following table lists the concatenation operators and operators for calculating table or string length in Lua language:

Operator	Description	Example
..	Concatenate two strings	a..b, where a is "Hello", b is "World", and the output result is "Hello World".
	##Unary operator, returns the length of a string or table.	#"Hello" Return 5

Example

We can use the following examples to understand the connection operator and calculation table more thoroughly Or application of string length operators:

a = "Hello "
b = "World"

print("连接字符串 a 和 b ", a..b )

print("b 字符串长度 ",#b )

print("字符串 Test 长度 ",#"Test" )

print("w3cschoolphp中文网网址长度 ",#"www.w3cschool.cc" )

The execution result of the above program is:

连接字符串 a 和 b 	Hello World
b 字符串长度 	5
字符串 Test 长度 	4
w3cschoolphp中文网网址长度 	16

Operator priority

In order from high to low:

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

All binary operators except ^ and .. are left connected.

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)

Example

We can use the following example to have a more thorough understanding of the priority of Lua language operators:

a = 20
b = 10
c = 15
d = 5

e = (a + b) * c / d;-- ( 30 * 15 ) / 5
print("(a + b) * c / d 运算值为  :",e )

e = ((a + b) * c) / d; -- (30 * 15 ) / 5
print("((a + b) * c) / d 运算值为 :",e )

e = (a + b) * (c / d);-- (30) * (15/5)
print("(a + b) * (c / d) 运算值为 :",e )

e = a + (b * c) / d;  -- 20 + (150/5)
print("a + (b * c) / d 运算值为   :",e )

The execution result of the above program is:

(a + b) * c / d 运算值为  :	90.0
((a + b) * c) / d 运算值为 :	90.0
(a + b) * (c / d) 运算值为 :	90.0
a + (b * c) / d 运算值为   :	50.0

Lua operators

Arithmetic operators

Examples

Logic Operators

Examples

Other operators

Example

Operator priority

Example

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