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The split function creates a list of the parts of the string that are separated by what matches the regular expression. In this example, a line is divided into a list of its own comma-separated parts, and this list is then assigned to the @words array.
Perl poetry is the practice of writing poems that can be compiled as legal Perl code, for example the piece known as "Black Perl". Perl poetry is made possible by the large number of English words that are used in the Perl language. New poems are regularly submitted to the community at PerlMonks. [148]
Perl provides three loop control keywords that all accept an optional loop label as an argument. If no label is specified, the keywords act on the innermost loop. Within nested loops, the use of labels enables control to move from an inner loop to an outer one, or out of the outer loop altogether.
What follows are examples of "Hello, World" implemented in different styles of modules. It must be understood that a module is not necessary in Perl; functions and code can be defined and used anywhere. This is just for example purposes. Contrast with Java where a class is always necessary. A real "Hello, World" function would be written like so:
#!usr/bin/perl – called the "shebang line", after the hash symbol (#) and ! (bang) at the beginning of the line. It is also known as the interpreter directive. # – the number sign, also called the hash symbol. In Perl, the # indicates the start of a comment. It instructs perl to ignore the rest of the line and not execute it as script code.
A procedural program is composed of one or more units or modules, either user coded or provided in a code library; each module is composed of one or more procedures, also called a function, routine, subroutine, or method, depending on the language. Examples of procedural languages include:
List comprehension is a syntactic construct available in some programming languages for creating a list based on existing lists. It follows the form of the mathematical set-builder notation (set comprehension) as distinct from the use of map and filter functions.
In Perl, foreach (which is equivalent to the shorter for) can be used to traverse elements of a list. The expression which denotes the collection to loop over is evaluated in list-context and each item of the resulting list is, in turn, aliased to the loop variable. List literal example: