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Perl Language Reference Manual
by Larry Wall and others
Paperback (6"x9"), 724 pages
ISBN 9781906966027
RRP £29.95 ($39.95)

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17.12 WARNINGS

The lone dot that ends a format can also prematurely end a mail message passing through a misconfigured Internet mailer (and based on experience, such misconfiguration is the rule, not the exception). So when sending format code through mail, you should indent it so that the format-ending dot is not on the left margin; this will prevent SMTP cutoff.

Lexical variables (declared with "my") are not visible within a format unless the format is declared within the scope of the lexical variable. (They weren't visible at all before version 5.001.)

Formats are the only part of Perl that unconditionally use information from a program's locale; if a program's environment specifies an LC_NUMERIC locale, it is always used to specify the decimal point character in formatted output. Perl ignores all other aspects of locale handling unless the use locale pragma is in effect. Formatted output cannot be controlled by use locale because the pragma is tied to the block structure of the program, and, for historical reasons, formats exist outside that block structure. See "Perl locale handling (internationalization and localization)" (perllocale) in the Perl Unicode and Locales Manual for further discussion of locale handling.

Within strings that are to be displayed in a fixed length text field, each control character is substituted by a space. (But remember the special meaning of \r when using fill mode.) This is done to avoid misalignment when control characters "disappear" on some output media.

ISBN 9781906966027Perl Language Reference ManualSee the print edition