search
HomeBackend DevelopmentPHP Tutorialphp合并数组array_merge函数运算符加号与的区别_php技巧

array_merge在参考手册中的说明如下:
array_merge() 将两个或多个数组的单元合并起来,一个数组中的值附加在前一个数组的后面。返回作为结果的数组。
如果输入的数组中有相同的字符串键名,则该键名后面的值将覆盖前一个值。然而,如果数组包含数字键名,后面的值将不会覆盖原来的值,而是附加到后面。
  两个的区别是:
  1.数组键名为数字键名时,要合并的两个数组中有同名数字KEY的时候,使用array_merge()不会覆盖掉原来的值,而使用“+”合并数组则会把最先出现的值作为最终结果返回,而把后面的数组拥有相同键名的那些值“抛弃”掉(注意:不是覆盖而是保留最先出现的那个值)。例子:

复制代码 代码如下:

  $array1 = array(1=>'0');
  $array2 = array(1=> "data");
  $result1 = $array2 + $array1;/*结果为$array2的值*/
  print_r($result);
$result = $array1 + $array2 ;/*结果为$array1的值*/
print_r($result);
$result3 = array_merge($array2,$array1);/*结果为$array2和$array1的值,键名被重新分配*/
print_r($result3);
$result4 = array_merge($array1,$array2);/*结果为$array1和$array2的值,键名被重新分配*/
print_r($result4);

输出结果为: 
复制代码 代码如下:

Array
(
[1] => data
)
Array
(
[1] => 0
)
Array
(
[0] => data
[1] => 0
)
Array
(
[0] => 0
[1] => data
)

  2.当相同数组键名为字符时,“+”运算符与键名为数字时一样,但array_merge()此时会覆盖掉前面相同键名的值。
  例子:
  
复制代码 代码如下:

$array1 = array('asd'=>'0');
  $array2 = array('asd' => "data");
  $result1 = $array2 + $array1;/*结果为$array2的值*/
  print_r($result);
$result = $array1 + $array2 ;/*结果为$array1的值*/
print_r($result);
$result3 = array_merge($array2,$array1);/*结果为$array1*/
print_r($result3);
$result4 = array_merge($array1,$array2);/*结果为$array2*/
print_r($result4);

输出结果为:
复制代码 代码如下:

Array
(
[asd] => data
)
Array
(
[asd] => 0
)
Array
(
[asd] => 0
)
Array
(
[asd] => data
)
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
Explain the concept of session locking.Explain the concept of session locking.Apr 29, 2025 am 12:39 AM

Sessionlockingisatechniqueusedtoensureauser'ssessionremainsexclusivetooneuseratatime.Itiscrucialforpreventingdatacorruptionandsecuritybreachesinmulti-userapplications.Sessionlockingisimplementedusingserver-sidelockingmechanisms,suchasReentrantLockinJ

Are there any alternatives to PHP sessions?Are there any alternatives to PHP sessions?Apr 29, 2025 am 12:36 AM

Alternatives to PHP sessions include Cookies, Token-based Authentication, Database-based Sessions, and Redis/Memcached. 1.Cookies manage sessions by storing data on the client, which is simple but low in security. 2.Token-based Authentication uses tokens to verify users, which is highly secure but requires additional logic. 3.Database-basedSessions stores data in the database, which has good scalability but may affect performance. 4. Redis/Memcached uses distributed cache to improve performance and scalability, but requires additional matching

What is the full form of PHP?What is the full form of PHP?Apr 28, 2025 pm 04:58 PM

The article discusses PHP, detailing its full form, main uses in web development, comparison with Python and Java, and its ease of learning for beginners.

How does PHP handle form data?How does PHP handle form data?Apr 28, 2025 pm 04:57 PM

PHP handles form data using $\_POST and $\_GET superglobals, with security ensured through validation, sanitization, and secure database interactions.

What is the difference between PHP and ASP.NET?What is the difference between PHP and ASP.NET?Apr 28, 2025 pm 04:56 PM

The article compares PHP and ASP.NET, focusing on their suitability for large-scale web applications, performance differences, and security features. Both are viable for large projects, but PHP is open-source and platform-independent, while ASP.NET,

Is PHP a case-sensitive language?Is PHP a case-sensitive language?Apr 28, 2025 pm 04:55 PM

PHP's case sensitivity varies: functions are insensitive, while variables and classes are sensitive. Best practices include consistent naming and using case-insensitive functions for comparisons.

How do you redirect a page in PHP?How do you redirect a page in PHP?Apr 28, 2025 pm 04:54 PM

The article discusses various methods for page redirection in PHP, focusing on the header() function and addressing common issues like "headers already sent" errors.

Explain type hinting in PHPExplain type hinting in PHPApr 28, 2025 pm 04:52 PM

Article discusses type hinting in PHP, a feature for specifying expected data types in functions. Main issue is improving code quality and readability through type enforcement.

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

MantisBT

MantisBT

Mantis is an easy-to-deploy web-based defect tracking tool designed to aid in product defect tracking. It requires PHP, MySQL and a web server. Check out our demo and hosting services.

EditPlus Chinese cracked version

EditPlus Chinese cracked version

Small size, syntax highlighting, does not support code prompt function

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

ZendStudio 13.5.1 Mac

ZendStudio 13.5.1 Mac

Powerful PHP integrated development environment

SecLists

SecLists

SecLists is the ultimate security tester's companion. It is a collection of various types of lists that are frequently used during security assessments, all in one place. SecLists helps make security testing more efficient and productive by conveniently providing all the lists a security tester might need. List types include usernames, passwords, URLs, fuzzing payloads, sensitive data patterns, web shells, and more. The tester can simply pull this repository onto a new test machine and he will have access to every type of list he needs.