5.30. Perl operator

An operator is a symbol that tells the compiler to perform specific mathematical or logical operations, such as: 3+2=5 .

Perl language comes with a wealth of operators, so let’s take a lookat a few commonly used ones:

Arithmetic operator
Comparison operator
Logical operator
Assignment operator
Bit operator
Quotation mark operator
Other operators
Operator precedence

5.30.1. Arithmetic operator #

In the table instance, we set the variable $a as 10 and $b as 20 .

Operator	Description	Example
`+`	Addition operation	$a + $b results in 30
`-`	Subtraction operation	$a-$b results in-10
`*`	Multiplication operation	$a * $b the result is 200
`/`	Division operation	$b / $a result is 2
`%`	Remainder operation, remainder after division	$b $a result is 0
`**`	Multiplying power	The result is 10 to the power of 20

Example #

#!/usr/bin/perl$a=10;$b=20;print"\\$a =$a,\\$b =$b\\n";$c=$a+$b;print'$a + $b ='.$c."\\n";$c=$a-$b;print'$a - $b ='.$c."\\n";$c=$a*$b;print'$a * $b ='.$c."\\n";$c=$a/$b; print '$a/$b='. $c . "\n"; $c = $a % $b; print'$a%$b='. $c. "\n"; $a = 2; $b = 4; $c = $a ** $b; print'$a**$b='. $c . "\n"; 

The output of the above program execution is as follows:

$a = 10 , $b = 20 $a + $b = 30 $a - $b = -10 $a * $b = 200 $a / $b = 0.5 $a % $b = 10 $a ** $b = 16 

5.30.2. Comparison operator #

In the table instance, we set the variable $a as 10 and $b as 20 .

Operator	Description	Example
==	Check whether the values of the two operands are equal, and if so, the condition is true, otherwise false.	($a = = $b) is false
! =	Check whether the values of the two operands are equal, and if not, the condition is true, otherwise false.	($a! = $b) is true.
< = >	Check whether the values of the two operands are equal, return-1 if the number on the left is less than the number on the right, 0 if the number on the left is greater than the number on the right, return 1 if the number on the left is greater than that on the right.	($a < = > $b) returns-1.
>	Check whether the value of the left Operand is greater than the value of theright Operand. If so, the condition is true, otherwise it is false.	($a > $b) returns false.
<	Check whether the value of the left Operand is less than the value of the right Operand, and if so, the condition is true, otherwise false is returned.	($a < $b) returns true.
>=	Check whether the value of the left Operand is greater than or equal to the value of the right Operand, and if so, the condition is true, otherwise false is returned.	($a > = $b) returns false.
<=	Check whether the value of the left Operand is less than or equal to the value of the right Operand, and if so, the condition is true, otherwise false is returned.	($a < = $b) returns true.

Example #

#/ Usr/bin/perl $a=10$ B=20; Print " $a=$a, $b =$b n "; if ($a==$b) {print" $a== $b result true n ";}else {print" $a== $b Result false n ";} if ($a!=$b) {print" $a!= $b Result True n ";} else {print" $a!= $b result false n ";} $c=$a<=>$b; print" $a <=> $b returns the result of $c n "; if ($a>$b) {print" $a> $b True n ";}else {print" $a> $b result false n ";} if ($a>=$b) {print" $a >=\\$b result true n ";}else {print" $a>= $b result False n ";} if ($a<$b) {print" $a< $b result true n ";}else {print" $a < $bResult false n ";} if ($a<=$b) {print" $a<= $bResult True n ";} else {print" $a<= $b result false n ";} 

The output of the above program execution is as follows:

$a=10, $b=20 $a==$b result false $a!=$ B Result true $a<=>$b returns -1 $a>$b result false $a>=$b result false $a<$b result true $a<=$b result true 

In the following table example, set the variable $a to "abc" and $b to "xyz" , and then use a comparison operator to calculate the result.

Operator	Description	Example
Lt	Check whether the string on the left is less than the string on the right, and return true if not, false otherwise.	($a lt $b) returns true.
Gt	Check whether the string on the left is larger than the string on the right, and return true if not, false otherwise.	($a gt $b) returns false.
Le	Check whether the string on the left is less than or equal to the string on the right, and return true if not, false otherwise.	($a le $b) returns true
Ge	Check whether the string on the left is greater than or equal to the string on the right, and return true if not, false otherwise.	($a ge $b) returns false.
Eq	Check whether the string on the left is equal to the string on the right, and return true if not, false otherwise.	($an eq $b) returns false.
Ne	Check whether the string on the left is not equal to the string on the right, and return true if not, false otherwise.	($a ne $b) returns true
Cmp	If the string on the left is greater than the string on the right, it returns 1, if equality returns 0, and if the string on the left is less thanthe string on the right, it returns-1.	($a cmp $b) returns-1.

Example #

#/ Usr/bin/perl $a="abc"$ B="xyz"; Print " $a=$a, $b =$b n "; if ($alt $b) {print" $alt b returns true n ";}else {print" $a lt $b Return false n ";} if ($agt $b) {print" $a gt $b Return True n ";}else {print" $a gt $b returns false n ";} if ($ale $b) {print" $a Le $b returns true n ";}else {print" $a le $b returns False n ";} if ($age $b) {print" $a ge $b returns true n ";}else {print" $a Ge $b returns false n ";} if ($ane $b) {print" $a ne $b returns True n ";} else {print" $a ne $b returns false n ";} c=$acmp $b; print" $a Cmp $b returns $c n "; 

The output of the above program execution is as follows:

$a=abc, $b=xyz Abc lt $b returns true $a gt $b returns false $a le $b returns true $a ge $b returns false $a ne $b returns true $a cmp $b returns -1 

5.30.3. Assignment operator #

In the table instance, we set the variable $a as 10 and $b as 20 .

Operator	Description	Example
=	A simple assignment operator that assigns the value of the right Operand to the left Operand	`$c = $a + $b` Will put `$a + $b` the value assigned to the `$c`
+=	Add the assignment operator to assign the result of the right Operand plus the left Operand to the left Operand	`$c += $a` equal to `$c = $c + $a`
-=	Subtract and assign the left Operand to the left Operand minus the result ofthe right Operand	`$c -= $a` equal to `$c = $c - $a`
`*=`	Multiply and assign the operator to assign the result of the right Operand multiplied by the left Operand to the left Operand	`$c = $a` equal to `$c = $c $a`
`/=`	Divide and assign the operator to assign the result of dividing the left Operand by the right Operand to the left Operand	`$c /= $a` equal to `$c = $c / $a`
`%=`	Find the module and assignment operator, find the module assignment of two operands to the left Operand	`$c %= $a` equal to `$c = $c % a`
`**=`	Power and assignment operator to assign the power of two operands to the left Operand	`$c = $a` equal to `$c = $c $a`

Example #

#/ Usr/bin/perl $a=10$ B=20; Print " $a=$a, $b =$b n "; $c=$a+$b; print" After assignment $c=$c n "; $c+=$a; print" $c =$c, operation statement $c+= $a n "; $c -=$a; print" $c=$c, operation statement $c -=\\$a n "; $c *=$a; print" $c=$c, operation statement $c *= $a n "; $c/=$a; Print " $c=$c, operation statement $c/= $a n"$ C%=$a; Print " $c=$c, arithmetic statement $c%= $a n"$ C=2$ A=4; Print " $a=$a, \\$c=$c n "; $c * *=$a; print" $c=$c, arithmetic statement $c * *= $a n "; 

The output of the above program execution is as follows:

$a=10, $b=20 After assignment, $c=30 $c=40, operation statement $c+=$a $c=30, operation statement $c -=$a $c=300, operation statement $c *=$a $c=30, operation statement $c/=$a $c=0, operation statement $c%=$a $a=4, $c=2 $c=16, operation statement $c * *=$a 

5.30.4. Bit operation #

The bit operator acts on the bit and performs the operation bit by bit.

Set $a = 60 and $b = 13 , now represented in binary format, as follows:

$a = 0011 1100 $b = 0000 1101 ----------------- $a&$b = 0000 1100 $a|$b = 0011 1101 $a^$b = 0011 0001 ~$a = 1100 0011 

Perl supported bit operators are shown in the following table:

Operator	Description	Example
&	If it exists in both operands, the binary AND operator copies a bit to the result.	($a & $b) will get 12 with a binary of 0000 1100
	If it exists in any Operand, the binary OR operator copies a bit into the result.	($a \| $b) will get 61 with a binary of 0011 1101
^	If it exists in one of the operands but not in both operands, the binary XORoperator copies a bit to the result.	($a ^ $b) will get 49, with a binary of 0011 0001
~	The binary anti-code operator is a unary operator with a “flip” bit effect, that is, 0 becomes 1, 1 becomes 0.	(~ $a) will get-61, the binary is 1100 0011, the inverse form of a signed binary number.
< <	Binary left shift operator. The value of the left Operand moves the number of digits specified by the right Operand to the left.	$a < < 2 will get 240. the binary is 1111 0000.
> >	Binary right shift operator. The value of the left Operand moves the number of digits specified by the right Operand to the right.	$a > > 2 will get 15, binary 0000 1111

Example #

#!/usr/bin/perluse integer;$a=60;$b=13;print"\\$a =$a,\\$b =$b\\n";$c=$a&$b;print"\\$a &\\$b =$c\\n";$c=$a\|$b;print"\\$a \|\\$b =$c\\n";$c=$a^$b;print"\\$a ^\\$b =$c\\n";$c= ~$a;print"~\\$a =$c\\n";$c=$a<<2 2='$c\\n";$c=$a' ;print"\\$a <<>>2;print"\\$a >> 2 =$c\\n";

The output of the above program execution is as follows:

 $a = 60 , $b = 13 $a & $b = 12 $a | $b = 61 $a ^ $b = 49 ~$a = -61 $a << 2 = 240 $a >> 2 = 15  

5.30.5. Logical operator #

Perl logical operators are shown in the following table.

In the table instance, we set the variable $a as true and $b as false .

Operator	Description	Example
and	Logic and operators. If both operands are true, the condition is true.	($an and $b) is false.
&&	C-style logic and operators. If both operands are true, the condition is true	($a & & $b) is false.
or	Logic or operator. If either of the operands is nonzero, the condition is true.	($an or $b) is true.
\|\|	C style logic or operator. If either of the operands is nonzero, the condition is true.	($a \|\| $b) is true.
not	Logical non-operator. Used to reverse the logical state of operands. If the condition is true, the logical non-operator will make it false.	Not ($an and $b) is true.

Example #

 #!/usr/bin/perl$a=true;$b=false;print"\\$a =$a,\\$b =$b\\n";$c=($aand$b);print"\\$a and\\$b =$c\\n";$c=($a&&$b);print"\\$a &&\\$b =$c\\n";$c=($aor$b);print"\\$a or\\$b =$c\\n";$c=($a\|\|$b);print"\\$a \|\|\\$b =$c\\n";$a=0;$c=not($a);print"not(\\$a)=$c\\n";  

The output of the above program execution is as follows:

 $a = true , $b = false $a and $b = false $a && $b = false $a or $b = true $a || $b = true not($a)= 1  

5.30.6. Quotation mark operation #

Perl quote operators are shown in the following table.

Operator	Description	Example
Q{}	Add single quotation marks to a string	Q {abcd} result is’ abcd’
Qq{}	Add double quotation marks to a string	Qq {abcd} result is “abcd”
Qx{}	Add backquotes to a string	Qx {abcd} result is abcd

Example #

 #!/usr/bin/perl$a=10;$b=q{a = $a};print"q{a =\\$a} =$b\\n";$b=qq{a =$a};print"qq{a =\\$a} =$b\\n";# Executing the date command using unix $t=qx{date}; print "qx{date}=$t\\n";  

The output of the above program execution is as follows:

Q {a=$a}=a=$a Qq {a=$a}=a=10 Qx {date}=Friday, June 10, 2016 16:22:33 CST

5.30.7. Other operators #

In addition to the operators we mentioned above Perl The following operators are also supported:

Operator	Description	Example
.	Dot (.) Used to concatenate two strings.	If $a = “run”, $b = “oob”, and $a.accounb results in “runoob”
X	The x operator returns the number of times the string is repeated.	(‘-‘x 3) the output is -.
		(2. 5) the output is (2, 3, 4, 5)
++	Self-increment operator, the integer value increases by 1	$a = 10, $asides + output to 11
–	Self-subtraction operator, integer value minus 1	$a = 10, $aMel-output to 9
->	The arrow is used to specify the method of a class	$obj- > $a represents the $a method of the object $obj.

Example #

 #!/usr/bin/perl$a="run";$b="oob";print"\\$a =$a，\\$b =$b\\n";$c=$a.$b;print"\\$a .\\$b =$c\\n";$c="-"x3;print"\\"-\\"x 3 =$c\\n";@c=(2..5);print"(2..5) = @c\\n";$a=10;$b=15;print"\\$a =$a，\\$b =$b\\n";$a++;$c=$a;print"\\$a implement\\$a++ =$c\\n";$b--;$c=$b;print"\\$b implement \\$b-- =$c\\n";  

The output of the above program execution is as follows:

 $a = run ， $b = oob $a . $b = runoob "-" x 3 = --- (2..5) = 2 3 4 5 $a = 10 ， $b = 15 $a implement $a++ = 11 $b implement $b-- = 14  

5.30.8. Operator precedence #

The following table lists Perl operator precedence of the language:

Operator	Binding property
`++,?--`	None
`-,?~,?!`	From right to left
`**`	From right to left
`=~,?!~`	From left to right
`*,?/,?%,?x`	From left to right
`+,?-,?.`	From left to right
`<<,?>>`	From left to right
`-e,?-r,`	None
`<,?<=,?>,?>=,?lt,?le,?gt,?ge`	From left to right
`==,?!=,?<=>,?eq,?ne,?cmp`	From left to right
`&`	From left to right
`\|,?^`	From left to right
`&&`	From left to right
`\|\|`	From left to right
`..`	From left to right
`??and?:`	From right to left
`=,?+=,?-=,?*=,`	From right to left
`Others`
`,`	From left to right
`not`	From left to right
`and`	From left to right
`or,?xor`	From left to right

Example #

 #!/usr/bin/perl$a=20;$b=10;$c=15;$d=5;$e;print"\\$a =$a,\\$b =$b,\\$c =$c，\\$d =$d\\n";$e=($a+$b)*$c/$d; print "(\$a + \\$b) * \\$c/\\$d=$e\\n";$e= (($a+$b) *$c)/$d; print"((\\$a+ \\$b)* \\$c)/\\$d = $e\n"; $e = ($a + $b) * ($c/$d);print"(\\$a +\\$b) * (\\$c /\\$d ) =$e\\n";$e=$a+($b*$c)/$d; print "\$a + (\$b * \\$c )/\\$d=$e\\n";  

The output of the above program execution is as follows:

 $a = 20, $b = 10, $c = 15 ，$d = 5 ($a + $b) * $c / $d = 90 (($a + $b) * $c) / $d = 90 ($a + $b) * ($c / $d ) = 90 $a + ($b * $c )/ $d = 50  

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