$~ is the format : Special Variables « Language Basics « Perl

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Perl » Language Basics » Special Variables

$~ is the format


   



format standardformat_top =

                  Employees

First Name   Last Name    ID       Extension

--------------------------------------------

.



format standardformat =

@<<<<<<<<<<<<@<<<<<<<<<<<<@<<<<<<<<@<<<<

$firstname   $lastname    $ID      $extension

.



$firstname = "A"; 

$lastname = "B";

$ID = 1234; 

$extension = x456;



open FILEHANDLE, ">report.frm" or die "Can't open file";



select FILEHANDLE;



$~ = standardformat;

$^ = standardformat_top;



write;

close;

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11.	A program that uses the $(dollar), variable.
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31.	Compare value entered with number with underscore
32.	Error message is stored in $!
33.	Extracts information from the $] variable.
34.	$! is the error number
35.	$! stores the error message
36.	$" is the separator
37.	$# is the default format
38.	$(dollar), is the separator
39.	$MATCH = $&
40.	$SIG{__DIE__}
41.	$SIG{__WARN__} = 'IGNORE';
42.	$SIG{__WARN__} = sub {die "Warning: $_[0]"};
43.	$\ is 'END_OF_OUTPUT'
44.	$^ is the format header
45.	$^O stores the name of the operating system
46.	$^S: is inside eval
47.	$^W: Check the '-w switch'
48.	$^X: get the Perl execuatable file name
49.	$_ for print function
50.	$_ stores the user input
51.	%INC values
52.	File-searching program using $ARGV.
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54.	Get local time from $^T
55.	If $_contains needle, the string is printed.
56.	Integer signal
57.	Lines Remaining on the Page: $-
58.	List all command line argument
59.	Local builtin var
60.	Locate all numbers less than 6
61.	Manipuate @_ and return @_
62.	Mannually change the $1 variable
63.	Match: $&
64.	Perl 5 Built-In Variables
65.	Perl's modules reside in the directories named in the @INC array, or subdirectories
66.	Perl's special arrays
67.	Perl's special variables
68.	Postmatch $'
69.	Prematch: $`
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71.	Print the default variable's ($_) value
72.	Quick Sum
73.	Read and set environment variables?
74.	Read lines from supplied filenames
75.	Reference element in @_
76.	Resetting array base
77.	Retrieving the Entire Pattern: $&
78.	Saving in the $& special scalar
79.	Set the $/ and chomp
80.	Special Variables
81.	System variables that control how write sends output to a file
82.	Test of open and die with $!.
83.	The $_ Scalar Variable
84.	The @* field
85.	The @ISA Array and Calling Methods
86.	The Argument Vector @ARGV
87.	The Pattern-Matching Operator and $_
88.	The Substitution Operator and $_
89.	The code executes a line of code you type as long as that line doesn't start with a #
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98.	Using $_ variable with while statement
99.	Using %SIG to define our own signal handlers
100.	Using @_ directly
101.	Using __LINE__ to output line number
102.	Using eof and <> together.
103.	Using the $. variable.
104.	Using the $;(dollar and semicolon) variable.
105.	Using the @_ to reference the parameter
106.	Using the Default Variable $_
107.	Using the diamond operator with @ARGV
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110.	Using tr to convert all file names passed in to uppercase
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114.	You display the name of the current Perl package with __PACKAGE__.
115.	You display the name of the current file with the __FILE__ token
116.	foreach (@_)
117.	foreach loop and $_
118.	or die $!
119.	or die $^E;
120.	print "Hello, $ENV{USER}!\n";
121.	print $INC{'English.pm'};
122.	print $]; (Perl version number)
123.	print out all pm library location
124.	prints out each element of @ARGV separately
125.	shift: defaults to shifting @ARGV
126.	time - $^T
127.	undef $/;

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