PHP array learning returns all common factors and the greatest common factor between two given numbers-PHP Tutorial-php.cn

Home

Backend Development

PHP Tutorial

PHP array learning returns all common factors and the greatest common factor between two given numbers

青灯夜游

Aug 13, 2021 pm 04:07 PM

phparraygreatest common divisor

In the previous article "PHP Array Learning: Changing the Uppercase or Lowercase of Keys/Values", we introduced the method of changing the case of array key names or key values in PHP associative arrays. This time we look at how to get all the common factors of two integers and find the largest common factor (approximate) number. Interested friends can learn about it~

First of all, let’s understandwhat is The number of common factors (approximately) and the number of greatest common factors (approximately)?

The factor (approximation) number refers to a number that can divide an integer. The common factor (approximation) number is a number that can divide several integers at the same time. There can be multiple common divisors that can divide several integers at the same time, and the largest one is the greatest common factor.

For example: the numbers 30 and 40, their common factors are 1, 2, 5, and 10; among them, 10 is the largest, so the greatest common factor of the numbers 30 and 40 is 10.

So how do we use PHP to get the common factors and the greatest common factor between two integers a and b?

Ideas:

1. Obtain the factors between two integers a and b respectively (this is described in detail in PHP Loop Learning Eight above), Then store these factors into an array. Here, take the number 30 as an example, use a for loop to find all factors:

for($i=1;$i<30;$i++){
    if($a%$i==0){//分解因数
        $arr1[]=$i;
    }
}

Output this array$arr1

var_dump($arr1);

Look at the result:

PHP array learning returns all common factors and the greatest common factor between two given numbers

It can be seen that the factors of the number 30 are: 1, 2, 3, 5, 6, 10, 15.

Using the above method, we get all the factors of the number 40 and store them in an array $arr2:

PHP array learning returns all common factors and the greatest common factor between two given numbers

It can be seen that the number 40 The factors are: 1, 2, 4, 5, 8, 10, 20.

2. After all the factors of the two integers have been obtained, you can use the array_intersect() function to find all the common factors between them. (The array_intersect() function can calculate the intersection of two arrays. If you don’t understand, you can read "PHP Array Learning: How to Compare Two Arrays to Find the Intersection").

$result=array_intersect($arr1,$arr2);
var_dump($result);

The output result is:

PHP array learning returns all common factors and the greatest common factor between two given numbers

In this way, we can get all the common factors of the numbers 30 and 40: 1, 2, 5, 10.

All the common factors of 3, 30 and 40 are in the intersection array$result, we can use the max() function to get the largest one in the array number, the greatest common factor.

$max=max($result);
echo "最大公因数为： $max";

The output result is:

PHP array learning returns all common factors and the greatest common factor between two given numbers

OK, done! Encapsulate the above code in a function:

<?php
header("Content-type:text/html;charset=utf-8");
function gcd($a,$b){
$arr1=array();
$arr2=array();
for($i=1;$i<$a;$i++){
    if($a%$i==0){//分解因数
        $arr1[]=$i;
    }
}
for($i=1;$i<$b;$i++){
    if($b%$i==0){//分解因数
        $arr2[]=$i;
    }
}

$result=array_intersect($arr1,$arr2);
echo "数 $a 和 $b 的公因（约）数有：";
foreach($result as $value){
	echo $value." ， ";
}

$max=max($result);
echo "<br>最大公因数为： $max  <br><br>";
}
gcd(30,40);
gcd(12,16);
?>

Output result:

PHP array learning returns all common factors and the greatest common factor between two given numbers

##That’s it for now, if there is anything else you want to know Yes, you can click this. → →

php video tutorial

Finally, I would like to recommend a free video tutorial on PHP arrays:

PHP function array array function video explanation, come and learn!

The above is the detailed content of PHP array learning returns all common factors and the greatest common factor between two given numbers. For more information, please follow other related articles on the PHP Chinese website!

Statement

The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

How does PHP type hinting work, including scalar types, return types, union types, and nullable types?Apr 17, 2025 am 12:25 AM

PHP type prompts to improve code quality and readability. 1) Scalar type tips: Since PHP7.0, basic data types are allowed to be specified in function parameters, such as int, float, etc. 2) Return type prompt: Ensure the consistency of the function return value type. 3) Union type prompt: Since PHP8.0, multiple types are allowed to be specified in function parameters or return values. 4) Nullable type prompt: Allows to include null values and handle functions that may return null values.

How does PHP handle object cloning (clone keyword) and the __clone magic method?Apr 17, 2025 am 12:24 AM

In PHP, use the clone keyword to create a copy of the object and customize the cloning behavior through the \_\_clone magic method. 1. Use the clone keyword to make a shallow copy, cloning the object's properties but not the object's properties. 2. The \_\_clone method can deeply copy nested objects to avoid shallow copying problems. 3. Pay attention to avoid circular references and performance problems in cloning, and optimize cloning operations to improve efficiency.

PHP vs. Python: Use Cases and ApplicationsApr 17, 2025 am 12:23 AM

PHP is suitable for web development and content management systems, and Python is suitable for data science, machine learning and automation scripts. 1.PHP performs well in building fast and scalable websites and applications and is commonly used in CMS such as WordPress. 2. Python has performed outstandingly in the fields of data science and machine learning, with rich libraries such as NumPy and TensorFlow.

Describe different HTTP caching headers (e.g., Cache-Control, ETag, Last-Modified).Apr 17, 2025 am 12:22 AM

Key players in HTTP cache headers include Cache-Control, ETag, and Last-Modified. 1.Cache-Control is used to control caching policies. Example: Cache-Control:max-age=3600,public. 2. ETag verifies resource changes through unique identifiers, example: ETag: "686897696a7c876b7e". 3.Last-Modified indicates the resource's last modification time, example: Last-Modified:Wed,21Oct201507:28:00GMT.

Explain secure password hashing in PHP (e.g., password_hash, password_verify). Why not use MD5 or SHA1?Apr 17, 2025 am 12:06 AM

In PHP, password_hash and password_verify functions should be used to implement secure password hashing, and MD5 or SHA1 should not be used. 1) password_hash generates a hash containing salt values to enhance security. 2) Password_verify verify password and ensure security by comparing hash values. 3) MD5 and SHA1 are vulnerable and lack salt values, and are not suitable for modern password security.

PHP: An Introduction to the Server-Side Scripting LanguageApr 16, 2025 am 12:18 AM

PHP is a server-side scripting language used for dynamic web development and server-side applications. 1.PHP is an interpreted language that does not require compilation and is suitable for rapid development. 2. PHP code is embedded in HTML, making it easy to develop web pages. 3. PHP processes server-side logic, generates HTML output, and supports user interaction and data processing. 4. PHP can interact with the database, process form submission, and execute server-side tasks.

PHP and the Web: Exploring its Long-Term ImpactApr 16, 2025 am 12:17 AM

PHP has shaped the network over the past few decades and will continue to play an important role in web development. 1) PHP originated in 1994 and has become the first choice for developers due to its ease of use and seamless integration with MySQL. 2) Its core functions include generating dynamic content and integrating with the database, allowing the website to be updated in real time and displayed in personalized manner. 3) The wide application and ecosystem of PHP have driven its long-term impact, but it also faces version updates and security challenges. 4) Performance improvements in recent years, such as the release of PHP7, enable it to compete with modern languages. 5) In the future, PHP needs to deal with new challenges such as containerization and microservices, but its flexibility and active community make it adaptable.

Why Use PHP? Advantages and Benefits ExplainedApr 16, 2025 am 12:16 AM

The core benefits of PHP include ease of learning, strong web development support, rich libraries and frameworks, high performance and scalability, cross-platform compatibility, and cost-effectiveness. 1) Easy to learn and use, suitable for beginners; 2) Good integration with web servers and supports multiple databases; 3) Have powerful frameworks such as Laravel; 4) High performance can be achieved through optimization; 5) Support multiple operating systems; 6) Open source to reduce development costs.

See all articles