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Perl Language Reference Manual
by Larry Wall and others
Paperback (6"x9"), 724 pages
ISBN 9781906966027
RRP £29.95 ($39.95)

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2.8 Builtin operators and functions

Perl comes with a wide selection of builtin functions. Some of the ones we've already seen include print, sort and reverse. A list of them is given at the start of 9 and you can easily read about any given function by using perldoc -f functionname.

Perl operators are documented in full in 7, but here are a few of the most common ones:

+   addition
-   subtraction
*   multiplication
/   division
Numeric comparison
==  equality
!=  inequality
<   less than
>   greater than
<=  less than or equal
>=  greater than or equal
String comparison
eq  equality
ne  inequality
lt  less than
gt  greater than
le  less than or equal
ge  greater than or equal
(Why do we have separate numeric and string comparisons? Because we don't have special variable types, and Perl needs to know whether to sort numerically (where 99 is less than 100) or alphabetically (where 100 comes before 99).
Boolean logic
&&  and
||  or
!   not
(and, or and not aren't just in the above table as descriptions of the operators. They're also supported as operators in their own right. They're more readable than the C-style operators, but have different precedence to && and friends. Check 7 for more detail.)
=   assignment
.   string concatenation
x   string multiplication
..  range operator (creates a list of numbers)

Many operators can be combined with a = as follows:

$a += 1;        # same as $a = $a + 1
$a -= 1;        # same as $a = $a - 1
$a .= "\n";     # same as $a = $a . "\n";
ISBN 9781906966027Perl Language Reference ManualSee the print edition