FAQ 7.2 What are all these $@%&* punctuation signs, and how do I know when to use them?

Discussion in 'Perl Misc' started by PerlFAQ Server, Feb 19, 2011.

  1. This is an excerpt from the latest version perlfaq7.pod, which
    comes with the standard Perl distribution. These postings aim to
    reduce the number of repeated questions as well as allow the community
    to review and update the answers. The latest version of the complete
    perlfaq is at http://faq.perl.org .


    7.2: What are all these $@%&* punctuation signs, and how do I know when to use them?

    They are type specifiers, as detailed in perldata:

    $ for scalar values (number, string or reference)
    @ for arrays
    % for hashes (associative arrays)
    & for subroutines (aka functions, procedures, methods)
    * for all types of that symbol name. In version 4 you used them like
    pointers, but in modern perls you can just use references.

    There are couple of other symbols that you're likely to encounter that
    aren't really type specifiers:

    <> are used for inputting a record from a filehandle.
    \ takes a reference to something.

    Note that <FILE> is *neither* the type specifier for files nor the name
    of the handle. It is the "<>" operator applied to the handle FILE. It
    reads one line (well, record--see "$/" in perlvar) from the handle FILE
    in scalar context, or *all* lines in list context. When performing open,
    close, or any other operation besides "<>" on files, or even when
    talking about the handle, do *not* use the brackets. These are correct:
    "eof(FH)", "seek(FH, 0, 2)" and "copying from STDIN to FILE".


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    PerlFAQ Server, Feb 19, 2011
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