What is the search algorithm in PHP array? How to find it?
There are many search algorithms in php. Which ones do you know? How do you understand the meaning of search algorithms? This article will take you to explore some mysteries about algorithms. Let’s discuss what is a search algorithm in an array? How to find it?
Related recommendations: What is the facade pattern in PHP? What are his strengths? What are the applicable scenarios?
Search algorithm:
Search algorithm meaning:
Search is to find a specific information element in a large amount of information. In computer applications, search is a commonly used basic operation.
The search algorithm refers to the code structure corresponding to the search process. It is to quickly locate the desired elements in medium and large arrays. .
Sequential search algorithm:
Sequential search is also called research search. Starting from the - end of the data structure linear table, it scans sequentially and scans the nodes in sequence. The keyword is compared with the given value k. If they are equal, the search is successful; if the node with the keyword equal to k is not found at the end of the scan, the search fails.
Let’s take the code as an example:
<?php
//查找算法
//顺序查找
$arr = array(1,3,6,8,23,68,100);
//顺序查找:从数组第一个元素开始，挨个匹配
function check_order($arr , $num){
//全部匹配
for($i = 0,$len = count($arr);$i <$len;$i++){
//判断
if($arr[$i] == $num){
return $i;
}
}
return false ;
}
var_dump(check_order($arr,5));
Binary search algorithm
Binary search requires linear table The nodes are listed in ascending or descending order according to the keyword value. The initial value k is used to compare with the keyword of the intermediate node. The intermediate node divides the linear table into two sub-tables. If they are equal, the search is successful; if they are not equal, then based on The comparison result between k and the key of the intermediate node determines which sub-table to search next, and so on recursively until the search is found or the search ends and it is found that there is no such node in the table.
Half algorithm idea:
1. Calculate the length of the array; .
2. Determine the pointer positions on the left and right sides; .
3. Find the middle position;
4. Match.
5. Then reset the boundaries according to the size.
<?php
//查找算法
//顺序查找
$arr = array(1,3,6,8,23,68,100);
//顺序查找:从数组第一个元素开始，挨个匹配
function check_order($arr , $num){
//全部匹配
for($i = 0,$len = count($arr);$i <$len;$i++){
//判断
if($arr[$i] == $num){
return $i;
}
}
return false ;
}
//var_dump(check_order($arr,5));
//二分查找算法
//1、 得到数组边界
$right = count($arr);
$left= 0;
$res = 3;
//2、循环匹配，
while($left <=$right){
//3、得到中间位置
$middle = floor(($right + $left) / 2);
//4、匹配数据.
if($arr[$middle] == $res){
echo $middle;
break;
}
//5、没有找到
if($arr[$middle] < $res){
//值在右边
$left = $middle + 1;
}else{
//值在左边
$right = $middle - 1;
Recommended learning: "PHP Video Tutorial"
The above is the detailed content of What is the search algorithm in PHP array? How to find it?. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
1664
14
1422
52
1316
25
1267
29
1240
24
Explain JSON Web Tokens (JWT) and their use case in PHP APIs.
Apr 05, 2025 am 12:04 AM
JWT is an open standard based on JSON, used to securely transmit information between parties, mainly for identity authentication and information exchange. 1. JWT consists of three parts: Header, Payload and Signature. 2. The working principle of JWT includes three steps: generating JWT, verifying JWT and parsing Payload. 3. When using JWT for authentication in PHP, JWT can be generated and verified, and user role and permission information can be included in advanced usage. 4. Common errors include signature verification failure, token expiration, and payload oversized. Debugging skills include using debugging tools and logging. 5. Performance optimization and best practices include using appropriate signature algorithms, setting validity periods reasonably,
Explain late static binding in PHP (static::).
Apr 03, 2025 am 12:04 AM
Static binding (static::) implements late static binding (LSB) in PHP, allowing calling classes to be referenced in static contexts rather than defining classes. 1) The parsing process is performed at runtime, 2) Look up the call class in the inheritance relationship, 3) It may bring performance overhead.
What are PHP magic methods (__construct, __destruct, __call, __get, __set, etc.) and provide use cases?
Apr 03, 2025 am 12:03 AM
What are the magic methods of PHP? PHP's magic methods include: 1.\_\_construct, used to initialize objects; 2.\_\_destruct, used to clean up resources; 3.\_\_call, handle non-existent method calls; 4.\_\_get, implement dynamic attribute access; 5.\_\_set, implement dynamic attribute settings. These methods are automatically called in certain situations, improving code flexibility and efficiency.
PHP and Python: Comparing Two Popular Programming Languages
Apr 14, 2025 am 12:13 AM
PHP and Python each have their own advantages, and choose according to project requirements. 1.PHP is suitable for web development, especially for rapid development and maintenance of websites. 2. Python is suitable for data science, machine learning and artificial intelligence, with concise syntax and suitable for beginners.
PHP in Action: Real-World Examples and Applications
Apr 14, 2025 am 12:19 AM
PHP is widely used in e-commerce, content management systems and API development. 1) E-commerce: used for shopping cart function and payment processing. 2) Content management system: used for dynamic content generation and user management. 3) API development: used for RESTful API development and API security. Through performance optimization and best practices, the efficiency and maintainability of PHP applications are improved.
PHP: A Key Language for Web Development
Apr 13, 2025 am 12:08 AM
PHP is a scripting language widely used on the server side, especially suitable for web development. 1.PHP can embed HTML, process HTTP requests and responses, and supports a variety of databases. 2.PHP is used to generate dynamic web content, process form data, access databases, etc., with strong community support and open source resources. 3. PHP is an interpreted language, and the execution process includes lexical analysis, grammatical analysis, compilation and execution. 4.PHP can be combined with MySQL for advanced applications such as user registration systems. 5. When debugging PHP, you can use functions such as error_reporting() and var_dump(). 6. Optimize PHP code to use caching mechanisms, optimize database queries and use built-in functions. 7
The Enduring Relevance of PHP: Is It Still Alive?
Apr 14, 2025 am 12:12 AM
PHP is still dynamic and still occupies an important position in the field of modern programming. 1) PHP's simplicity and powerful community support make it widely used in web development; 2) Its flexibility and stability make it outstanding in handling web forms, database operations and file processing; 3) PHP is constantly evolving and optimizing, suitable for beginners and experienced developers.
Explain the match expression (PHP 8 ) and how it differs from switch.
Apr 06, 2025 am 12:03 AM
In PHP8, match expressions are a new control structure that returns different results based on the value of the expression. 1) It is similar to a switch statement, but returns a value instead of an execution statement block. 2) The match expression is strictly compared (===), which improves security. 3) It avoids possible break omissions in switch statements and enhances the simplicity and readability of the code.
