Perl Functions: How to Create Your Own Functions in Perl

perl functionsIn programming, you will commonly find a specific section of code that performs a task. This section of code is known as a function. A function returns a value, and it can be used throughout your program countless times. Most programming languages, such as Perl, have prewritten functions in a library that you can use. Prewritten functions are a great asset for you, as they can streamline the programming process and remove countless lines of code that you would otherwise have had to write by hand.

In addition to prewritten functions though, you can create your own. Perl allows you to create functions for your own highly specialized task, and it is a great way for you to do something specific in your program, especially if that task needs to be done multiple times. Functions are a fundamental tool in Perl. If you want to learn how to program properly, then you will have to understand how functions work. If you don’t have any experience with Perl programming, but you want to learn about functions and other aspects of the language, check out the Udemy courses Beginning Perl and Learn Perl 5 By Doing It. 

When Should You Use Functions?

Functions are versatile ways to help you really organize your program and make your code easily readable. When you’re programming, it’s important to organize your code so that you can go through it quickly. As you create your program, you may write hundreds or even thousands of lines of code. With functions, you can break up that code into small chunks. Not only do functions help you organize your code, but if you have a problem, you can find it a lot easier by scanning through specific functions instead of the entire code.

The best way to use a function is to first outline the program idea that you have and see where functions would work best.

How do Functions Work?

When you call a function in Perl, the program jumps from reading one piece of the program and moves on to another, which is the function that is currently being called. Perl continues to execute the lines of code inside of the function until the function is finished. Once the function is done executing, Perl will go back to running other lines of code.

How to Write a Function

The best way to understand functions is to create your own. Before you start creating your functions though there are a few things that you should remember.

First of all, when you’re naming your function, your function name can only contain letters, numbers, and underscores. The first digit though must always be either a letter or an underscore.

It’s also very important to remember that functions are case-sensitive. This means that Afunction is different from afunction.

Below is the basic outline of a function.

sub name of function {
my ($firstparameter, $secondparameter) = @_;
statements_in_function;
return value;
}

By breaking down the function line by line, you can better see how it works. The first line in the function is name of function, which as the name suggests is where you will put the name of your function.

The second line in the code includes the parameters for your function. You don’t have to include parameters, but they can prove useful in many situations. Say that you wanted to find the coordinates on a three dimensional plane for your function. You would set parameters for the x, y, and z values.

The second to last is the statements in function, which determine what will happen after the parameters of the function have been set. You can do various things with the statements, such as create loops, manipulate values, etc. This part of the function can be as complicated or simple as you want.

The final line is value, and that is the result that is returned from the operations of the function. This is just a simple breakdown of a function. It’s also important to see a functioning example of one.

Examples of Functions

Functions can be used for various applications. Below you will see some of the ways you can use functions in your programs. The first example is a question and answer prompt.

question();
my $answer = the_answer();
question();
my $anotheranswer = the_answer();
sub question {
print “What is your mission?”;
return;
}
sub the_answer{ my $answer = <STDIN>;
chomp $answer;
return $answer;
}

Above is a simple line of code that involves creating and using a function. In the beginning of the code, we made a call to two functions the question function and the answer function. After that, there were three subroutines that were called. Subroutines are similar to functions, but unlike functions, subroutines don’t have to have a return value.

The first subroutine doesn’t do much. This subroutine just takes the function and prints out the string found inside.

On the other hand, the second subroutine does a bit more. The second subroutine uses the read-line operated and chomp in a single function. Inside of this subroutine or function, the user will have to enter in a value and then press enter for the subroutine return the string.

The way a function works may seem a little confusing to those who have never done any programming before – this is understandable. Perl programming requires you to understand a completely different language. The best way for you to do this is to get a firm grasp of programming and its concepts.

If you’re completely new to programming altogether and you find these concepts overwhelming, then you should check out the course Programming for Absolute Beginners. Although the course teaches you with the Python programming language, you can still transfer that knowledge and those skills over to Perl. Python is such a versatile and simple language to learn that many people use it as a way to prepare themselves for learning various other programming languages. In fact, there are several similarities and key differences between Perl and Python.

Programming Professionally 

Mastering programming can lead you to a great career. However, sometimes you will be forced to demonstrate just how skilled you are at programming as a part of your interview. People can be caught off guard by this, but there are ways for you to confidently program in a way that will help you get the job. Check out the Udemy course Coding for Interviews to learn how to confidently demonstrate your programming abilities for future employers.