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Printing from a Hash - Perl

Thanks for stopping by for this seventh part in the series on Perl Lists and Hashes. Here we will discuss working with a new way to store data known as a Hash. We'll cover the basics, such as how to create them, and how to locate data within them. You'll learn to add records, remove records, and much more. If there is time, we will also cover multidimensional lists.

TABLE OF CONTENTS:
  1. Perl Hashes
  2. Creating A Hash
  3. Printing from a Hash
  4. Printing All the Values or Keys in a Hash
  5. Alternative Methods for Creating Hashes
By: James Payne
Rating: starstarstarstarstar / 6
April 28, 2008

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There are several print methods that you can use with hashes. The first we will learn about is printing individual values from a hash. Here, we will use our previous list of different types of brownies to print from:


#!/usr/bin/perl

%Brownies = (1,'Chocolate ', 2,'Fudge ',3,'Vanilla ',4,'Peanut Butter

');

print $Brownies{1};

You will note that we use $Brownies in our print statement instead of %Brownies. This is because we are only printing a single value, and thus it becomes a variable. The result of this is:

  Chocolate

If we wanted to print more than one value from the hash, we would change the $Brownies variable to @Brownies, since there will be more than one value in it. Here is how we return two or more values:


#!/usr/bin/perl

%Brownies = (1,'Chocolate ', 2,'Fudge ',3,'Vanilla ',4,'Peanut Butter

');

print @Brownies{1,2};

This simplistic code returns the following:

  Chocolate Fudge

Note that the keys that refer to your values don't have to be numbers. Here, we will use some text instead:


#!/usr/bin/perl

%HowItIs = (Dumb,'You ', Fat,'YoMama ',UglyGenius,'James Payne

',Nerd,'PHP Programmers');

print @HowItIs{Dumb,Fat,Nerd};

This code assigns the value “You” to the key Dumb, “YoMama” to Fat, and so forth. When we run this program, it prints the following:

  You YoMama PHP Programmers

Another thing to remember is that your keys may not equal the same value, but the value inside your keys can. Let's say that in addition to being an ugly genius, I am also a nerd. Here is how I could assign myself to two keys:


#!/usr/bin/perl

%HowItIs = (Dumb,'You ', Fat,'YoMama ',UglyGenius,'James Payne

',Nerd,'James Payne');

print @HowItIs{UglyGenius,Nerd};

The result is of course:

  James Payne James Payne



 
 
>>> More Perl Programming Articles          >>> More By James Payne
 

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