Perl Error Variable
A • B • C • D • E F • G • H • I • L M • N • O • P • S T • U • X perlvar Perl 5 version 24.0 documentation Go to top • Download PDF Show page index • Show recent pages Home > Language reference > perlvar Please note: Many features of this site require JavaScript. You appear to have JavaScript disabled, or are running a non-JavaScript capable web browser. To get the best experience, please enable JavaScript or download a modern web browser such as Internet Explorer 8, Firefox, Safari, or Google Chrome. Recently read perlvar NAMEDESCRIPTIONThe Syntax of Variable NamesSPECIAL VARIABLESGeneral VariablesVariables related to regular expressionsVariables related to filehandlesError Variables Variables related to the interpreter stateDeprecated and removed variablesNAME perlvar - Perl predefined variables DESCRIPTION The Syntax of Variable Names Variable names in Perl can have several formats. Usually, they must begin with a letter or underscore, in which case they can be arbitrarily long (up to an internal limit of 251 characters) and may contain letters, digits, underscores, or the special sequence :: or '. In this case, the part before the last :: or ' is taken to be a package qualifier; see perlmod. A Unicode letter that is not ASCII is not considered to be a letter unless "use utf8" is in effect, and somewhat more complicated rules apply; see Identifier parsing in perldata for details. Perl variable names may also be a sequence of digits, a single punctuation character, or the two-character sequence: ^ (caret or CIRCUMFLEX ACCENT) followed by any one of the characters [][A-Z^_?\] . These names are all reserved for special uses by Perl; for example, the all-digits names are used to hold data captured by backreferences after a regular expression match. Since Perl v5.6.0, Perl variable names may also be alphanumeric strings preceded by a caret. These must all be written in the form ${^Foo} ; the braces are not optional. ${^Foo} denotes the scalar variable whose name is considered to be a control-F followed by two o 's. These variables are reserved for future special uses by Perl, except for the ones that begin with
Syntax Overview Perl - Data Types Perl - Variables Perl - Scalars Perl - Arrays Perl - Hashes Perl - IF...ELSE Perl - Loops Perl - Operators Perl - Date & Time Perl - Subroutines Perl - References Perl - Formats Perl - File I/O Perl - Directories Perl - Error Handling Perl - Special Variables Perl - Coding Standard Perl - Regular Expressions Perl - Sending Email Perl Advanced Perl - Socket Programming Perl - Object Oriented Perl - Database Access Perl - CGI Programming Perl - Packages & Modules Perl - Process Management Perl - http://perldoc.perl.org/perlvar.html Embedded Documentation Perl Useful Resources Perl - Questions and Answers Perl - Quick Guide Perl - Functions References Perl - Useful Resources Perl - Discussion Selected Reading Developer's Best Practices Questions and Answers Effective Resume Writing HR Interview Questions Computer Glossary Who is Who Perl - Special Variables Advertisements Previous Page Next Page There are some variables which have a predefined and special meaning in https://www.tutorialspoint.com/perl/perl_special_variables.htm Perl. They are the variables that use punctuation characters after the usual variable indicator ($, @, or %), such as $_ ( explained below ). Most of the special variables have an english like long name, e.g., Operating System Error variable $! can be written as $OS_ERROR. But if you are going to use english like names, then you would have to put one line use English; at the top of your program file. This guides the interpreter to pickup exact meaning of the variable. The most commonly used special variable is $_, which contains the default input and pattern-searching string. For example, in the following lines − #!/usr/bin/perl foreach ('hickory','dickory','doc') { print $_; print "\n"; } When executed, this will produce the following result − hickory dickory doc Again, let's check the same example without using $_ variable explicitly − #!/usr/bin/perl foreach ('hickory','dickory','doc') { print; print "\n"; } When executed, this will also produce the following result − hickory dickory doc The first time the loop is executed, "hickory" is printed. The second time around, "dickory" is printed, and the third time, "doc" is printed. That's because in each iteration of the loop, the cur
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