Latest web development tutorials

# Perl Operators

Operator tells the compiler to perform a specific mathematical or logical operation symbols such as: 3 + 2 = 5.

Perl language built a wealth of operators, we look at several common:

## Arithmetic operators

Form example we set the variable \$ a is 10, \$ b 20.

Operators description Examples
+ Adder \$ A + \$ b 30 results
- Subtraction \$ A - \$ b the result is -10
* Multiplication \$ A * \$ b 200 Results
/ Division \$ B / \$ a result 2
% Modulo operation, the remainder after the divisible \$ B% \$ a result is 0
** Exponentiation \$ A ** \$ b 10 20 th power results

### Examples

```#!/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 above program execution output is:

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

## Comparison

Form example we set the variable \$ a is 10, \$ b 20.

Operators description Examples
== Check the value of the two operands are equal, if they are equal then the condition is true, otherwise false. (\$ A == \$ b) is false
! = Check the value of the two operands are equal, if not equal condition is true, otherwise false. (\$ A! = \$ B) is true.
<=> Check the value of the two operands are equal, if the number is less than the number to the left of the right of return -1 return 0 if they are equal, if the number is greater than the number on the left to the right of return 1. (\$ A <=> \$ b) return -1.
> Check the value of the left operand is greater than the value of the right operand, and if the condition is true, otherwise false. (\$ A> \$ b) returns false.
< Check the value of the left operand is less than the value of the right operand, and if the condition is true, otherwise false. (\$ A <\$ b) returns true.
> = Check the value of the left operand is greater than or equal to the value of the right operand, and if the condition is true, otherwise false. (\$ A> = \$ b) returns false.
<= Check the value of the left operand is less than or equal to the value of the right operand, and if the condition is true, otherwise false. . (\$ A <= \$ b) returns true.

### Examples

```#!/usr/bin/perl

\$a = 10;
\$b = 20;

print "\\$a = \$a , \\$b = \$b\n";

if( \$a == \$b ){
print "\$a == \\$b 结果 true\n";
}else{
print "\\$a == \\$b 结果 false\n";
}

if( \$a != \$b ){
print "\\$a != \\$b 结果 true\n";
}else{
print "\\$a != \\$b 结果 false\n";
}

\$c = \$a <=> \$b;
print "\\$a <=> \\$b 返回 \$c\n";

if( \$a > \$b ){
print "\\$a > \\$b 结果 true\n";
}else{
print "\\$a > \\$b 结果 false\n";
}

if( \$a >= \$b ){
print "\\$a >= \\$b 结果 true\n";
}else{
print "\\$a >= \\$b 结果 false\n";
}

if( \$a < \$b ){
print "\\$a < \\$b 结果 true\n";
}else{
print "\\$a < \\$b 结果 false\n";
}

if( \$a <= \$b ){
print "\\$a <= \\$b 结果 true\n";
}else{
print "\\$a <= \\$b 结果 false\n";
}
```

The above program execution output is:

```\$a = 10 , \$b = 20
\$a == \$b 结果 false
\$a != \$b 结果 true
\$a <=> \$b 返回 -1
\$a > \$b 结果 false
\$a >= \$b 结果 false
\$a < \$b 结果 true
\$a <= \$b 结果 true
```

The following table instance variable \$ a is set to "abc", \$ b to "xyz", then use a comparison operator to calculate the results.

Operators description Examples
lt Check the string on the left is less than the string on the right to return if it is true, otherwise false. (\$ A lt \$ b) returns true.
gt Check whether the string on the left is greater than the string on the right to return if it is true, otherwise false. (\$ A gt \$ b) returns false.
le Check the string on the left is less than or equal to the string on the right, if it returns true, otherwise returns false. (\$ A le \$ b) Returns true
ge Check whether the string on the left is greater than or equal to the string on the right, if it returns true, otherwise returns false. (\$ A ge \$ b) returns false.
eq Check the string is equal to the string on the left to the right, if it is to return true, otherwise returns false. (\$ A eq \$ b) returns false.
ne Check the string on the left is not equal to the string on the right to return if it is true, otherwise false. (\$ A ne \$ b) Returns true
cmp If the string is greater than the right of the left string returns 1 if they are equal returns 0 if the string is the string to the right of the left is less than -1. (\$ A cmp \$ b) return -1.

### Examples

```#!/usr/bin/perl

\$a = "abc";
\$b = "xyz";

print "\\$a = \$a ，\\$b = \$b\n";

if( \$a lt \$b ){
print "\$a lt \\$b 返回 true\n";
}else{
print "\\$a lt \\$b 返回 false\n";
}

if( \$a gt \$b ){
print "\\$a gt \\$b 返回 true\n";
}else{
print "\\$a gt \\$b 返回 false\n";
}

if( \$a le \$b ){
print "\\$a le \\$b 返回 true\n";
}else{
print "\\$a le \\$b 返回 false\n";
}

if( \$a ge \$b ){
print "\\$a ge \\$b 返回 true\n";
}else{
print "\\$a ge \\$b 返回 false\n";
}

if( \$a ne \$b ){
print "\\$a ne \\$b 返回 true\n";
}else{
print "\\$a ne \\$b 返回 false\n";
}

\$c = \$a cmp \$b;
print "\\$a cmp \\$b 返回 \$c\n";
```

The above program execution output is:

```\$a = abc ，\$b = xyz
abc lt \$b 返回 true
\$a gt \$b 返回 false
\$a le \$b 返回 true
\$a ge \$b 返回 false
\$a ne \$b 返回 true
\$a cmp \$b 返回 -1
```

## Assignment Operators

Form example we set the variable \$ a is 10, \$ b 20.

Operators description Examples
= Simple assignment operator, the value on the right operand to the left operand \$ C = \$ a + \$ b \$ a + \$ b will assign the value of \$ c
+ = Canadian and assignment operator, the result of adding the left operand to the right operand assigned to the left operand \$ C + = \$ a is equal to \$ c = \$ c + \$ a
- = Save and assignment operators, the left operand to the right operand is subtracted assign the result to left operand \$ C - = \$ a is equal to \$ c = \$ c - \$ a
* = Multiply and assignment operator, the right of the left operand is multiplied by the operand assign the result to left operand \$ C * = \$ a is equal to \$ c = \$ c * \$ a
/ = In addition and assignment operators, the left operand divided by the right of the operand assign the result to left operand \$ C / = \$ a is equal to \$ c = \$ c / \$ a
% = Modulo and assignment operator, the sum of two operands mold assigned to the left operand \$ C% = \$ a is equal to \$ c = \$ c% a
** = Exponentiation and assignment operator, the sum of two operands multiplied by the power assigned to the left operand \$ C ** = \$ a is equal to \$ c = \$ c ** \$ a

### Examples

```#!/usr/bin/perl

\$a = 10;
\$b = 20;

print "\\$a = \$a ，\\$b = \$b\n";

\$c = \$a + \$b;
print "赋值后 \\$c = \$c\n";

\$c += \$a;
print "\\$c = \$c ，运算语句 \\$c += \\$a\n";

\$c -= \$a;
print "\\$c = \$c ，运算语句 \\$c -= \\$a\n";

\$c *= \$a;
print "\\$c = \$c ，运算语句 \\$c *= \\$a\n";

\$c /= \$a;
print "\\$c = \$c ，运算语句 \\$c /= \\$a\n";

\$c %= \$a;
print "\\$c = \$c ，运算语句 \\$c %= \\$a\n";

\$c = 2;
\$a = 4;
print "\\$a = \$a ， \\$c = \$c\n";
\$c **= \$a;
print "\\$c = \$c ，运算语句 \\$c **= \\$a\n";
```

The above program execution output is:

```\$a = 10 ，\$b = 20

\$c = 40 ，运算语句 \$c += \$a
\$c = 30 ，运算语句 \$c -= \$a
\$c = 300 ，运算语句 \$c *= \$a
\$c = 30 ，运算语句 \$c /= \$a
\$c = 0 ，运算语句 \$c %= \$a
\$a = 4 ， \$c = 2
\$c = 16 ，运算语句 \$c **= \$a
```

## Bit computing

Bitwise operators acting on the bit, and bit by bit operation.

Setting \$ a = 60, \$ b = 13, now represented in binary format, they are as follows:

```\$a = 0011 1100

\$b = 0000 1101

-----------------

\$a&\$b = 0000 1100

\$a|\$b = 0011 1101

\$a^\$b = 0011 0001

~\$a  = 1100 0011
```

Bit computing support Perl symbols as follows:

Operators description Examples
& If both exist in two operands, the binary AND operator to copy a result. (\$ A & \$ b) would be 12, to binary 0000 1100
| If present in either operand, the binary OR operator to copy a result. (\$ A | \$ b) would be 61, the binary is 00111101
^ If present in one of the operand, but not simultaneously exist in two operands, binary XOR operator a copy to the result. (\$ A ^ \$ b) would be 49, the binary is 00110001
~ Twos complement operator is a unary operator, a "flip" position effect. (~ \$ A) would be -61, binary 1100 0011 complement form of binary number with sign.
<< Binary left shift operator. The value of the left operand to move left and right operand the specified number of digits. \$ A << 2 will be 240, the binary is 11110000
>> Binary right shift operator. The value of the left operand move right operand the specified number of bits to the right. \$ A >> 2 will be 15, the binary is 0000 1111

### Examples

```#!/usr/bin/perl

use 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;
print "\\$a << 2 = \$c\n";

\$c = \$a >> 2;
print "\\$a >> 2 = \$c\n";
```

The above program execution output is:

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

## Logical Operators

Perl logical operators in the following table.

Form example we set the variable \$ a is true, \$ b is false.

Operators description Examples
and Logical AND operator operator. If both operands are true, the condition is true. (\$ A and \$ b) is false.
&& C-style logical AND operator operator. If both operands are true, the condition is true (\$ A && \$ b) is false.
or Logical OR operator. If both operands have any non-zero, the condition is true. (\$ A or \$ b) is true.
|| C-style Logical OR operator. If both operands have any non-zero, the condition is true. (\$ A || \$ b) is true.
not Logical NOT operator. It inverts the logic state of the operand. If the condition is true, the logical not operator will make it to false. not (\$ a and \$ b) is true.

### Examples

```#!/usr/bin/perl

\$a = true;
\$b = false;

print "\\$a = \$a , \\$b = \$b\n";

\$c = (\$a and \$b);
print "\\$a and \\$b = \$c\n";

\$c = (\$a  && \$b);
print "\\$a && \\$b = \$c\n";

\$c = (\$a or \$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 above program execution output is:

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

## Quotes operation

Perl quotes operators in the following table.

Operators description Examples
q {} The string with a single quote q {abcd} results for 'abcd'
qq {} A string of double quotes qq {abcd} results for "abcd"
qx {} The string with backquotes qx {abcd} the result is `abcd`

### Examples

```#!/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";

# 使用 unix 的 date 命令执行
\$t = qx{date};
print "qx{date} = \$t\n";
```

The above program execution output is:

```q{a = \$a} = a = \$a
qq{a = \$a} = a = 10
qx{date} = 2016年 6月10日 星期五 16时22分33秒 CST
```

## Other operators

In addition to the above we mentioned operators outside, Perl also supports the following operators:

Operators description Examples
. Dot (.) Is used to connect two strings. If \$ a = "run", \$ b = "oob", \$ a. \$ B results for "w3big"
x x operator returns a string of repetitions. ( '-' X 3) output is ---.
.. .. In a range of operators. (2..5) The output is (2, 3, 4, 5)
++ Increment operator, the integer value is incremented by 1 \$ A = 10, \$ a ++ will output 11
- Decrement operators, integer value reduced by 1 \$ A = 10, \$ a-- output 9
-> Specify a class method for Arrow \$ Obj -> \$ a representation of the object \$ obj \$ a method.

### Examples

```#!/usr/bin/perl

\$a = "run";
\$b = "oob";

print "\\$a  = \$a ， \\$b = \$b\n";

\$c = \$a . \$b;
print "\\$a . \\$b = \$c\n";

\$c = "-" x 3;
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 执行 \\$a++ = \$c\n";

\$b--;
\$c = \$b ;
print "\\$b 执行 \\$b-- = \$c\n";
```

The above program execution output is:

```\$a  = run ， \$b = oob
\$a . \$b = w3big
"-" x 3 = ---
(2..5) = 2 3 4 5
\$a  = 10 ， \$b = 15
\$a 执行 \$a++ = 11
\$b 执行 \$b-- = 14
```

## Operator Precedence

The following table lists the Perl language operator precedence:

Operators operator Binding
++ - no
-, ~,! Right to left
** Right to left
= ~! ~ From left to right
*, /,%, X From left to right
+, -,. From left to right
<< >> From left to right
-e, -r, no
<, <=,>,> =, 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: Right to left
=, + =, - =, * =, Right to left
other
, From left to right
not From left to right
and From left to right
or, xor From left to right

### Examples

```#!/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 above program execution output is:

```\$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
```