php數(shù)組相加 array(“a”)+array(“b”)結(jié)果還是array(“a”)
Jun 13, 2016 am 11:57 AM
在網(wǎng)上看到一道題:
array("a")+array("b")的結(jié)果是___
A.array("a","b")
B.array("b","a")
C.array("b")
D.array("a")
答案:D
php兩個(gè)數(shù)組相加,為什么結(jié)果還是不變呢?
因?yàn)?,它們等效于array("0″=>"a")+array("0″=>"b"),它們的鍵名相同,前者不能被后者覆蓋,如果是array("0″=>"a")+array("0″=>"b","1″=>"c"),那么結(jié)果等于array("0″=>"a","1″=>"c")
如果是同一個(gè)數(shù)組里面,有相同的鍵名會(huì)出現(xiàn)什么情況?
看一段php官方手冊(cè)中的代碼:
復(fù)制代碼 代碼如下:
$switching = array(???????? 10, // key = 0
??????????????????? 5??? =>? 6,
??????????????????? 3??? =>? 7,?
??????????????????? 'a'? =>? 4,
??????????????????????????? 11, // key = 6 (maximum of integer-indices was 5)
??????????????????? '8'? =>? 2, // key = 8 (integer!)
??????????????????? '02' => 77, // key = '02'
??????????????????? 0??? => 12? // the value 10 will be overwritten by 12
????????????????? );
可見(jiàn),同一個(gè)數(shù)組里面如果有相同的鍵名,則前面一個(gè)鍵名的值將會(huì)被覆蓋(overwritten)。

Hot AI Tools

Undress AI Tool
Undress images for free

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

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

PHPhasthreecommentstyles://,#forsingle-lineand/.../formulti-line.Usecommentstoexplainwhycodeexists,notwhatitdoes.MarkTODO/FIXMEitemsanddisablecodetemporarilyduringdebugging.Avoidover-commentingsimplelogic.Writeconcise,grammaticallycorrectcommentsandu

The key steps to install PHP on Windows include: 1. Download the appropriate PHP version and decompress it. It is recommended to use ThreadSafe version with Apache or NonThreadSafe version with Nginx; 2. Configure the php.ini file and rename php.ini-development or php.ini-production to php.ini; 3. Add the PHP path to the system environment variable Path for command line use; 4. Test whether PHP is installed successfully, execute php-v through the command line and run the built-in server to test the parsing capabilities; 5. If you use Apache, you need to configure P in httpd.conf

The basic syntax of PHP includes four key points: 1. The PHP tag must be ended, and the use of complete tags is recommended; 2. Echo and print are commonly used for output content, among which echo supports multiple parameters and is more efficient; 3. The annotation methods include //, # and //, to improve code readability; 4. Each statement must end with a semicolon, and spaces and line breaks do not affect execution but affect readability. Mastering these basic rules can help write clear and stable PHP code.

How to start writing your first PHP script? First, set up the local development environment, install XAMPP/MAMP/LAMP, and use a text editor to understand the server's running principle. Secondly, create a file called hello.php, enter the basic code and run the test. Third, learn to use PHP and HTML to achieve dynamic content output. Finally, pay attention to common errors such as missing semicolons, citation issues, and file extension errors, and enable error reports for debugging.

PHPisaserver-sidescriptinglanguageusedforwebdevelopment,especiallyfordynamicwebsitesandCMSplatformslikeWordPress.Itrunsontheserver,processesdata,interactswithdatabases,andsendsHTMLtobrowsers.Commonusesincludeuserauthentication,e-commerceplatforms,for

The steps to install PHP8 on Ubuntu are: 1. Update the software package list; 2. Install PHP8 and basic components; 3. Check the version to confirm that the installation is successful; 4. Install additional modules as needed. Windows users can download and decompress the ZIP package, then modify the configuration file, enable extensions, and add the path to environment variables. macOS users recommend using Homebrew to install, and perform steps such as adding tap, installing PHP8, setting the default version and verifying the version. Although the installation methods are different under different systems, the process is clear, so you can choose the right method according to the purpose.

TohandlefileoperationsinPHP,useappropriatefunctionsandmodes.1.Toreadafile,usefile_get_contents()forsmallfilesorfgets()inaloopforline-by-lineprocessing.2.Towritetoafile,usefile_put_contents()forsimplewritesorappendingwiththeFILE_APPENDflag,orfwrite()w

The key to writing Python's ifelse statements is to understand the logical structure and details. 1. The infrastructure is to execute a piece of code if conditions are established, otherwise the else part is executed, else is optional; 2. Multi-condition judgment is implemented with elif, and it is executed sequentially and stopped once it is met; 3. Nested if is used for further subdivision judgment, it is recommended not to exceed two layers; 4. A ternary expression can be used to replace simple ifelse in a simple scenario. Only by paying attention to indentation, conditional order and logical integrity can we write clear and stable judgment codes.
