Article Categories
- All Categories
-
Data Structure
-
Networking
-
RDBMS
-
Operating System
-
Java
-
MS Excel
-
iOS
-
HTML
-
CSS
-
Android
-
Python
-
C Programming
-
C++
-
C#
-
MongoDB
-
MySQL
-
Javascript
-
PHP
-
Economics & Finance
Articles on Trending Technologies
Technical articles with clear explanations and examples
Replacing Array Elements in Perl
Now we are going to introduce one more function called splice(), which has the following syntax −Syntaxsplice @ARRAY, OFFSET [ , LENGTH [ , LIST ] ]This function will remove the elements of @ARRAY designated by OFFSET and LENGTH, and replaces them with LIST if specified. Finally, it returns the elements removed from the array. Following is the example −Example#!/usr/bin/perl @nums = (1..20); print "Before - @nums"; splice(@nums, 5, 5, 21..25); print "After - @nums";OutputThis will produce the following result −Before - 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 ...
Read MoreTransform Perl Arrays to Strings
We can use the join() function in Perl to rejoin the array elements and form one long scalar string. This function has the following syntax −Syntaxjoin EXPR, LISTThis function joins the separate strings of LIST into a single string with fields separated by the value of EXPR and returns the string. Following is the example −Example#!/usr/bin/perl # define Strings $var_string = "Rain-Drops-On-Roses-And-Whiskers-On-Kittens"; $var_names = "Larry, David, Roger, Ken, Michael, Tom"; # transform above strings into arrays. @string = split('-', $var_string); @names = split(', ', $var_names); $string1 = join( '-', @string ); $string2 = join( ', ', @names ); ...
Read MoreSorting Arrays in Perl
The sort() function in Perl sorts each element of an array according to the ASCII Numeric standards. This function has the following syntax −Syntaxsort [ SUBROUTINE ] LISTThis function sorts the LIST and returns the sorted array value. If SUBROUTINE is specified then specified logic inside the SUBROUTINE is applied while sorting the elements.Example#!/usr/bin/perl # define an array @foods = qw(pizza steak chicken burgers); print "Before: @foods"; # sort this array @foods = sort(@foods); print "After: @foods";OutputThis will produce the following result −Before: pizza steak chicken burgers After: burgers chicken pizza steakPlease note that sorting is performed based on the ...
Read MoreThe $[ Special Variable in Perl
Perl provides numerous special variables, which have their predefined meaning.We have a special variable, which is written as $[. This special variable is a scalar containing the first index of all arrays. Because Perl arrays have zero-based indexing, $[ will almost always be 0. But if you set $[ to 1 then all your arrays will use on-based indexing. It is recommended not to use any other indexing other than zero. However, let's take one example to show the usage of $[ variable −Example#!/usr/bin/perl # define an array @foods = qw(pizza steak chicken burgers); print "Foods: @foods"; # Let's reset ...
Read MoreMerging Arrays in Perl
Because an array in Perl is just a comma-separated sequence of values, you can combine them together as shown below −Example#!/usr/bin/perl @numbers = (1,3,(4,5,6)); print "numbers = @numbers";OutputThis will produce the following result −numbers = 1 3 4 5 6The embedded arrays just become a part of the main array as shown below −Example#!/usr/bin/perl @odd = (1,3,5); @even = (2, 4, 6); @numbers = (@odd, @even); print "numbers = @numbers";OutputThis will produce the following result −numbers = 1 3 5 2 4 6
Read MoreSelecting Elements from Lists in Perl
The list notation in Perl is identical to that for arrays. You can extract an element from an array by appending square brackets to the list and giving one or more indices −Example#!/usr/bin/perl $var = (5,4,3,2,1)[4]; print "value of var = $var"OutputThis will produce the following result −value of var = 1Similarly, we can extract slices, although without the requirement for a leading @ character −Example#!/usr/bin/perl @list = (5,4,3,2,1)[1..3]; print "Value of list = @list";OutputThis will produce the following result −Value of list = 4 3 2
Read MoreAccessing Hash Elements in Perl
When accessing individual elements from a hash in Perl, you must prefix the variable with a dollar sign ($) and then append the element key within curly brackets after the name of the variable. For example −Example#!/usr/bin/perl %data = ('John Paul' => 45, 'Lisa' => 30, 'Kumar' => 40); print "$data{'John Paul'}"; print "$data{'Lisa'}"; print "$data{'Kumar'}";OutputThis will produce the following result −45 30 40
Read MoreExtracting Keys and Values from Hash in Perl
You can get a list of all of the keys from a hash in Perl by using keys function, which has the following syntax −keys %HASHThis function returns an array of all the keys of the named hash. Following is the example −Example#!/usr/bin/perl %data = ('John Paul' => 45, 'Lisa' => 30, 'Kumar' => 40); @names = keys %data; print "$names[0]"; print "$names[1]"; print "$names[2]";OutputThis will produce the following result −Lisa John Paul KumarSimilarly, you can use values function to get a list of all the values. This function has the following syntax −Syntaxvalues %HASHThis function returns a normal array ...
Read MoreChecking for Key/Value Existence in Perl Hash
If you try to access a key/value pair from a hash in Perl that doesn't exist, you'll normally get the undefined value, and if you have warnings switched on, then you'll get a warning generated at run time. You can get around this by using the exists function, which returns true if the named key exists, irrespective of what its value might be −Example#!/usr/bin/perl %data = ('John Paul' => 45, 'Lisa' => 30, 'Kumar' => 40); if( exists($data{'Lisa'} ) ) { print "Lisa is $data{'Lisa'} years old"; } else { print "I don't know age of Lisa"; }Here ...
Read MoreGetting Hash Size in Perl
You can get the size - that is, the number of elements from a hash in Perl by using the scalar context on either keys or values. Simply saying first you have to get an array of either the keys or values and then you can get the size of the array as follows −Example#!/usr/bin/perl %data = ('John Paul' => 45, 'Lisa' => 30, 'Kumar' => 40); @keys = keys %data; $size = @keys; print "1 - Hash size: is $size"; @values = values %data; $size = @values; print "2 - Hash size: is $size";OutputThis will produce the following result −1 - Hash size: is 3 2 - Hash size: is 3
Read More