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Perl Data Types
Scalar data types
lists
Arrays
Hashes
Perl special variablesThese are predefined variables in perl like
$? : The status returned by the last pipe close, backtick (`` ) command, successful call to wait() or waitpid(), or from the system() operator. learn more
Summary
Scalar variables are prepended with the symbol $. For array and hash variables, the symbols are
@ and % respectively.
Scalar variables can be assigned a value by using the assignment operator =. A variable holds the
value undef by default.
Variable names are case-sensitive. They should start with an alphabet or an underscore character
( ). Subsequent characters may be decimal digits as well. Variables whose names not conforming
to this nomenclature are predened by Perl and serve special purposes.
Variable substitution means variables embedded in a double-quoted string will be substituted by
their respective values at the instant the string is evaluated.
The substr() function extracts a sequence of characters from a given string.
The length() function returns the number of characters in a given string.
A list is an ordered set of scalar values. An array is a list associated with a name.
An array may be created by assigning a list to an array variable.
Nested lists are merged to form a single list when the list is evaluated, with null lists removed.
The reverse() function returns a list whose items are identical to the input list except the items
are arranged in reverse order.
The push() function may be used to append a list of items to the end of an array.
The unshift() function prepends a list of items to the beginning of an array.
The subscript operator []can be used to access a subset of elements in a list or an array.
The pop() and shift() functions may be used to remove an item from an array. pop() removes
the last item while shift() removes the rst item.
splice() is a general purpose function to add or remove array elements.
join() concatenates a list of scalars into a string, inserting a string in between.
map() executes a given code block for each list element, and the results evaluated are combined
to form an array.
Searching an array is not efcient. A hash should be used instead.
A hash may be initialized by assigning it a list, whose elements are treated as a list of key-value
pairs.
To refer to a hash element, use curly braces with the key in between.
The delete() function may be used to remove a key-value pair from a hash.
You may use the exists() function
Perl functions
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Perl @ARGV %ENV
Perl Arrays
Perl Hash
Perl list
Perl references
Perl Scalar data types
Perl Special Variables
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Perl 5.10.1
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