B.10 Basic Operators

For more information on how operators work, consult the perlop documentation bundled with Perl.

B.10.1 Arithmetic Operators

Perl has the basic five arithmetic operators:

+

Addition

-

Subtraction

*

Multiplication

/

Division

**

Exponentiation

These operators work on both integers and floating-point values (and if you're not careful, strings as well).

Perl also has a modulus operator, which computes the remainder of two integers:

% modulus

For example, 17 % 3 is 2, because 2 is left over when you divide 3 into 17.

Perl also has autoincrement and autodecrement operators:

++ add one
-- subtract one

Unlike the previous six operators, these change a variable's value. $x++ adds one to $x, changing 4 to 5 (or a to b).

B.10.2 Bitwise Operators

All scalars, whether numbers or strings, are represented as sequences of individual bits "under the hood." Every once in a while, you need to manipulate those bits, and Perl provides five operators to help:

&

Bitwise and

|

Bitwise or

^

Bitwise xor

>>

Right shift

<<

Left shift

B.10.3 String Operators

Two strings may be concatenated—joined together end to end—with the dot operator:

'This is a ' . 'joined string'

This results in the value 'This is a joined string'.

A string may be repeated with the x operator:

print "Hear ye! " x 3;

This prints out:

Hear ye! Hear ye! Hear ye!

B.10.4 File Test Operators

File test operators are unary operators that test files for certain characteristics, such as -e $file, which returns true if the file $file exists. Table B-2 lists some available file test operators.

Table B-2. File test operators

Operator	Meaning
-r	File is readable
-w	File is writable
-x	File is executable
-o	File is owned by "you"
-e	File exists
-z	File has zero size in bytes
-s	File has nonzero size (returns size in bytes)
-f	File is a plain file
-d	File is a directory (a.k.a. folder)
-l	File is a symbolic link
-t	Filehandle is opened to a terminal
-T	File is a text file
-B	File is a binary file
-M	Age of file (at startup of program) in days since modification
-A	Age of file (at startup of program) in days since last access
-C	Age of file (at startup of program) in days since last inode change