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string, as is any single identifier within a hash
subscript. Our earlier example,



14/Jun/98 perl 5.005, patch 02 13





PERLDATA(1) Perl Programmers Reference Guide PERLDATA(1)


$days{'Feb'}

can be written as

$days{Feb}

and the quotes will be assumed automatically. But
anything more complicated in the subscript will be
interpreted as an expression.

Note that a single-quoted string must be separated from a
preceding word by a space, because single quote is a valid
(though deprecated) character in a variable name (see the
Packages entry in the _p_e_r_l_m_o_d manpage).

Three special literals are __FILE__, __LINE__, and
__PACKAGE__, which represent the current filename, line
number, and package name at that point in your program.
They may be used only as separate tokens; they will not be
interpolated into strings. If there is no current package
(due to an empty package; directive), __PACKAGE__ is the
undefined value.

The tokens __END__ and __DATA__ may be used to indicate
the logical end of the script before the actual end of
file. Any following text is ignored, but may be read via
a DATA filehandle: main::DATA for __END__, or
PACKNAME::DATA (where PACKNAME is the current package) for
__DATA__. The two control characters ^D and ^Z are
synonyms for __END__ (or __DATA__ in a module). See the
_S_e_l_f_L_o_a_d_e_r manpage for more description of __DATA__, and
an example of its use. Note that you cannot read from the
DATA filehandle in a BEGIN block: the BEGIN block is
executed as soon as it is seen (during compilation), at
which point the corresponding __DATA__ (or __END__) token
has not yet been seen.