FAQ 7.2 What are all these [email protected]%&* punctuation signs, and how do I know when to use them?


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7.2: What are all these [email protected]%&* 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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