EDUCBA

EDUCBA

MENUMENU
  • Free Tutorials
  • Free Courses
  • Certification Courses
  • 600+ Courses All in One Bundle
  • Login

Factorial in PHP

Home » Software Development » Software Development Tutorials » PHP Tutorial » Factorial in PHP

Factorial in PHP

Introduction to Factorial in PHP

Before we begin learning of Factorial in PHP, let us understand the term factorial. Factorial of a number is the product of all numbers starting from 1 up to the number itself. While calculating the product of all the numbers, the number is itself included.

Factorial of a number is calculated for positive integers only. The factorial of 0 is always 1 and the factorial of a negative number does not exist. It is denoted by ‘!’ preceded by the number. Example n! where n is the number

Start Your Free Software Development Course

Web development, programming languages, Software testing & others

So,

Factorial of 5! means factorial of 5

Factorial of 7! means factorial of 7

For example, the factorial of number 5 is:

5! =5*4*3*2*1 = 120

Similarly, the factorial of number 7 is:

7! = 7*6*5*4*3*2*1 = 5040

and so on..

Now how do we actually find the factorial, we can do it using

  1. for loop (without recursion)
  2. with recursion

Factorial Logic

The logic behind getting the factorial of the number is as per the following.

  1. Get the number whose factorial is to be calculated.
  2. Get all the numbers starting from 1 up to that number.
  3. Get the multiplication of all the numbers.

Remember the factorial of 0! = 1.

How to Find Factorial in PHP?

We will learn further using different methods to calculate factorial of the given number using PHP code. Like using recursion, recursion with user input, without recursion, without recursion with user input.

About Recursion

Like other languages PHP also supports Recursion. What is recursion? When a function calls itself is termed as recursion. A recursive function calls itself within the function.

Popular Course in this category
PHP Training (5 Courses, 3 Project)5 Online Courses | 3 Hands-on Project | 28+ Hours | Verifiable Certificate of Completion | Lifetime Access
4.5 (5,726 ratings)
Course Price

View Course

Related Courses
Java Servlet Training (6 Courses, 12 Projects)All in One Software Development Bundle (600+ Courses, 50+ projects)

Example #1

In the following PHP program factorial of number 5 is calculated. This is a simple program using for loop. This for loop is iterated on the sequence of numbers starting from the number till 1 is reached.

Code:

<?php
//example to calculate factorial of a number using simple for loop
//declaring the input number as 5
$input=5;
//declaring the fact variable as 1
$fact =1;
//iterating using for loop
for($i=$input; $i>=1;$i--) {
// multiply each number up to 5 by its previous consecutive number
$fact = $fact * $i;
}
// Print output of the program
echo '<br>'. 'The factorial of the number 5 is '. $fact
?>

Output:

Factorial in PHP Example 1

Example #2

In the below program, we have used a simple HTML form with an input text and a submit button. The input box is used to get user input. The submit button is used to submit the form data. Followed by that is the PHP code to iterate for loop wherein all the logic is present, which we learned in the previous program. So now the same logic is used with an input form.

If the user inputs a positive number through the input box in the form, the factorial of that number is calculated and the result is printed.

Code:

<html>
<head>
<title> Factorial Program</title>
</head>
<body>
<form method="POST">
<label>Enter a number</label>
<input type="text" name="number" />
<input type="submit" name="submit" value="Submit" />
</form>
<?php
// example to demonstrate factorial of a number using form
if($_POST['submit'] == "Submit") {
$input = $_POST['number'];
$fact=1;
//iterating using for loop
for($i=$input; $i>=1;$i--) {
$fact = $fact * $i;
}
// Print output of the program
echo '<br>'. 'The factorial of the number '.$input.' is ' . $fact;
}
?>
</body>
</html>

Output :

Fact of Example 2

Example #3

In the above two programs, we didn’t wrap the logic within a function. Here we have enclosed the main logic in a function and then called that function to calculate the factorial of the given number in PHP. Here the name of the function is Factorial_Function which finds the factorial of number 8.

Code:

//example to calculate factorial of a number using function
//defining the factorial function
function Factorial_Function($number) {
$input = $number;
$fact=1;
//iterating using for loop
for($i=$input; $i>=1;$i--) {
$fact = $fact * $i;
}
return $fact;
}
//calling the factorial function
$result = Factorial_Function(8);
echo 'Factorial of the number 8 is '.$result;
?>

Output :

Fact of Example 3

Example #4

We know that recursion is calling a function within a function. In the following example, we will use recursion and find the factorial of the number using PHP code. The main logic is wrapped in a function name Factorial_Function. Within this function if the input is greater that one, then the same function is called again and if the input is less than or equal to 1 then one is returned.

Using Recursion

Code:

<?php
//Example to demonstrate factorial of a number using recursion
//function containing logic of factorial
function Factorial_Function($input)
{
// if the input is less than or equal to 1 then return
if($input <=1) {
return 1;
}
// else do a recursive call and continue to find the factorial
return $input * Factorial_Function($input-1);  //doing a recursive call
}
echo "Factorial of 9 is ".Factorial_Function(9);
?>

Output :

Using Recursion Method

Example #5

We have now learned about recursion. In the following program, we have used recursion, the recursion is applied to the number which is the input from the user in this example.

Code:

<html>
<head>
<title> Factorial Program</title>
</head>
<body>
<form method="POST">
<label>Enter a number</label>
<input type="text" name="number" />
<input type="submit" name="submit" value="Submit" />
</form>
<?php
// example to demonstrate factorial of a number using form
function Factorial_Function($input)
{
// if the input is less than or equal to 1 then return
if($input <=1) {
return 1;
}
// else do a recursive call and continue to find the factorial
return $input * Factorial_Function($input-1); //doing a recursive call
}
if(!empty($_POST['number'])){
$input = $_POST['number'];
// Print output of the program
echo '<br>'. 'The factorial of the number '.$input.' is ' . Factorial_Function($input);
}
?>
</body>
</html>
 

Output:

Fact of Example 5

Conclusion

This article has covered all the explanations and examples for finding the factorial of a number using PHP. Examples are explained using recursive and non-recursive ways, along with recursion explanation in context with the program. Hope this article was found informative to learn and grasp well.

Recommended Articles

This is a guide to Factorial in PHP. Here we discuss the basic concept and how to find the factorial of a number in PHP with different examples. You may also look at the following article to learn more –

  1. PHP Math Functions
  2. PHP String Functions
  3. PHP Constants
  4. Factorial in Java

PHP Training (5 Courses, 3 Project)

5 Online Courses

3 Hands-on Project

28+ Hours

Verifiable Certificate of Completion

Lifetime Access

Learn More

0 Shares
Share
Tweet
Share
Primary Sidebar
PHP Tutorial
  • Programs
    • Patterns in PHP
    • Star Patterns in PHP
    • Swapping in PHP
    • Fibonacci Series PHP
    • Factorial in PHP
    • Reverse String in PHP
    • Square Root in PHP
    • Random Number Generator in PHP
    • Palindrome in PHP
    • Prime Numbers in PHP
    • Armstrong Number in PHP
    • Socket Programming in PHP
    • Login Page in PHP
    • PHP Login Template
    • PHP Object to String
  • PHP Basic
    • Introduction To PHP
    • What is PHP
    • PHP Keywords
    • Advantages of PHP
    • Career In PHP
    • Comments in PHP
    • PHP Commands
    • PHP Frameworks
    • PHP Compiler
    • Variables in PHP
    • PHP Superglobal Variables
    • PHP Versions
    • Object in PHP
    • What is Drupal
    • Top PHP Frameworks
    • WebStorm IDE
    • What is phpMyAdmin?
    • PhpStorm
    • Install phpMyAdmin
    • Phalcon Model
  • Data Types
    • PHP Data Types
    • PHP Integer
    • PHP Booleans
  • Operators
    • PHP Operators
    • Arithmetic Operators in PHP
    • Comparison Operators in PHP
    • Logical Operators in PHP
    • Bitwise Operators in PHP
    • Ternary Operator in PHP
    • PHP String Operators
  • Control Statements
    • Control Statement in PHP
    • PHP if Statement
    • if else Statement in PHP
    • elseif in PHP
    • PHP Switch Statement
    • Continue in PHP
    • Break in PHP
  • Loops
    • PHP Loops
    • For Loop in PHP
    • PHP Do While Loop
    • PHP While Loop
    • While Loop in PHP
    • Foreach Loop in PHP
  • Constructor
    • Constructor in PHP
    • Destructor in PHP
  • State Management
    • Cookie in PHP
    • Sessions in PHP
  • Array
    • What is PHP Array
    • Arrays in PHP
    • 2D Arrays in PHP
    • Associative Array in PHP 
    • Multidimensional Array in PHP
    • Indexed Array in PHP
    • PHP Array Functions
    • PHP unset Array
    • PHP Append Array
    • PHP Array Search
    • PHP Split Array
    • PHP array_push()
    • PHP array_pop()
  • Functions
    • Functions in PHP
    • PHP Math Functions
    • PHP Recursive Function
    • PHP String Functions
    • Hashing Function in PHP
    • Date Function in PHP
    • PHP Anonymous Function
    • Calendar in PHP
    • PHP Call Function
    • PHP Pass by Reference
    • PHP ucfirst()
    • PHP ucwords()
    • trim() in PHP
    • isset() Function in PHP
    • PHP replace
    • PHP fpm
    • PHP strpos
    • preg_match in PHP
    • PHP preg_replace()
    • PHP ob_start()
    • PHP Reflection
    • PHP Split String
    • PHP URL
    • PHP preg_match_all
    • PHP strtoupper()
    • PHP preg_split()
    • PHP substr_replace()
    • PHP setlocale()
    • PHP substr_count()
    • PHP Serialize
    • PHP strlen()
    • PHP async
    • PHP Date Time Functions
    • PHP timezone
    • PHP Data Object
    • print_r() in PHP
    • PHP header()
    • PHP strip_tags()
    • PHP chop()
    • PHP MD5()
    • PHP unset()
    • PHP crypt()
    • PHP wordwrap()
    • PHP is_null()
    • PHP strtok()
    • PHP bin2hex()
    • PHP parse_str()
    • PHP levenshtein()
    • PHP addslashes()
    • PHP strtotime
    • PHP sha1()
    • PHP explode()
    • PHP sscanf()
    • PHP require_once
    • PHP Zip Files
    • PHP $_SERVER
    • PHP $_POST
    • PHP Include and Require
    • PHP POST Method
  • Advanced
    • Overloading in PHP
    • Overriding in PHP
    • Method Overloading in PHP
    • Inheritance in PHP
    • Multiple Inheritance in PHP
    • PHP Interface
    • Encapsulation in PHP
    • PHP Constants
    • PHP Magic Constants
    • PHP Regular Expressions
    • PHP GET Method
    • PHP Annotations
    • PHP Encryption
    • PHP file Functions
    • PHP readfile
    • PHP?Write File
    • PHP Append File
    • PHP Type Hinting
    • PHP Filters
    • PHP Float
    • PHP Form
    • PHP Form Validation
    • Sorting in PHP
    • PHP usort()
    • PHP Stack Trace
    • PHP Stack Overflow
    • PHP Pagination
    • PHP implode
    • Polymorphism in PHP
    • Abstract Class in PHP
    • PHP Final Class
    • PHP Custom Exception
    • error_reporting() in PHP
    • PHP Log Errors
    • Access Modifiers in PHP
    • PHP Change Date Format
    • Static Method in PHP
    • PHP File Handling
    • PHP Output Buffering
    • Get IP Address in PHP
    • Upload a File in PHP
    • String in PHP
    • Public Function in PHP
    • Private in PHP
    • Protected in PHP
    • basename in PHP
    • Validation in PHP
    • PHP mail()
    • PHP Email Form
    • PHP Directory
    • PHP Create Session
    • PHP include_once
    • PHP json_decode
    • PHP XMLWriter
    • PHP XML Reader
    • PHP XML Parser
    • PHP XML into Array
    • Phalcon Framework
  • Database
    • PHP Database Connection
    • How to Connect Database to PHP
  • Interview Questions
    • PHP Interview Questions
    • PHP OOP Interview Questions
    • CakePHP Interview Questions
    • Core PHP Interview Questions

Related Courses

PHP Training Course

Java Servlet Training

Software Development Course Training

Footer
About Us
  • Blog
  • Who is EDUCBA?
  • Sign Up
  • Corporate Training
  • Certificate from Top Institutions
  • Contact Us
  • Verifiable Certificate
  • Reviews
  • Terms and Conditions
  • Privacy Policy
  •  
Apps
  • iPhone & iPad
  • Android
Resources
  • Free Courses
  • Java Tutorials
  • Python Tutorials
  • All Tutorials
Certification Courses
  • All Courses
  • Software Development Course - All in One Bundle
  • Become a Python Developer
  • Java Course
  • Become a Selenium Automation Tester
  • Become an IoT Developer
  • ASP.NET Course
  • VB.NET Course
  • PHP Course

© 2020 - EDUCBA. ALL RIGHTS RESERVED. THE CERTIFICATION NAMES ARE THE TRADEMARKS OF THEIR RESPECTIVE OWNERS.

EDUCBA
Free Software Development Course

Web development, programming languages, Software testing & others

*Please provide your correct email id. Login details for this Free course will be emailed to you
Book Your One Instructor : One Learner Free Class

Let’s Get Started

This website or its third-party tools use cookies, which are necessary to its functioning and required to achieve the purposes illustrated in the cookie policy. By closing this banner, scrolling this page, clicking a link or continuing to browse otherwise, you agree to our Privacy Policy

EDUCBA

*Please provide your correct email id. Login details for this Free course will be emailed to you
EDUCBA Login

Forgot Password?

EDUCBA
Free Software Development Course

Web development, programming languages, Software testing & others

*Please provide your correct email id. Login details for this Free course will be emailed to you

Special Offer - PHP Training (5 Courses, 3 Project) Learn More