


Summary of commonly used functions and global variables in PHP (recommended)
This article introduces to you a summary (recommended) of commonly used functions and global variables in PHP. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.
1. PHP built-in function
A
array_shift() deletes the first element in the array
array_pop() Delete the last element in the array
array_multisort() Return an ascending array
C
call_user_func_array() Call the callback function, and Call an array as a parameter of the callback function
D
define() define constant
debug_backtrace() trace code call information
E
error_reporting(0) Turn off error reporting
error_reporting(E_ERROR | E_WARNING | E_PARSE) Report runtime errors
error_reporting(E_ALL) Report all errors
ini_set("error_reporting", E_ALL) Equivalent to error_reporting(E_ALL)
error_reporting(E_ALL & ~E_NOTICE) Reports all errors except E_NOTICE
explode() will Split the string into an array
implode() Splice the elements in the array into a string
G
1.getenv() Get the value of the environment variable
$_SERVER['HTTP_HOST'] = getenv('HTTP_HOST');
H
header() Sends the original HTTP header to the client
I
is_file() Determines whether it is a file
ini_get() Gets the value of a configuration option
is_set() Whether it has been defined
is_null() Whether it is empty
P
1. phpversion() Current PHP version
R
require_once() Loading File
S
str_replace() Replace some characters in a string with other characters (case sensitive)
strlen() Get a string Length
substr() Return part of the string
str_repalce() Replace part of the string with another part
strtolower() Convert to lowercase
spl_autoload_register() Automatic loading
spl_autoload_extensions() Returns the automatically loaded file extension
U
unset() Destroy
V
1. version_compare( string $version1
, string $version2
[, string $operator
] ) Compare the first version number of PHP version
version1
. version2 The second version number operator operator <, lt, <=, le, >、 gt、>=、 ge、==、 =、eq , !=, <> and ne
For example:
if (version_compare(phpversion(), '5.6.0', '<')) { exit('PHP5.6+ Required'); }
2. Super global variables
$_SERVER
$_SERVER['DOCUMENT_ROOT']; The document root where the currently running script is located
$_SERVER['DOCUMENT_FILENAME'] The absolute path of the currently executing script
$_SERVER['PHP_SELF'] The file name of the currently executing script
$_SERVER['HTTP_HOST'] Get the current host
$_SERVER['PATH_TRANSLATED'] The base path where the current script is located, non-document root directory
$_SERVER['REQUEST_URI'] The current request path
$ _SERVER['QUERY_STRING'] Query string
$_SERVER['SERVER_PORT'] Server port
$_SERVER['HTTPS'] HTTPS request
Type operator
instanceof Determines whether a variable is an instance of a class
3. Common PHP encapsulated functions:
1. Determination Is it an HTTPS request?
// 检查是否是HTTPS请求 if ((isset($_SERVER['HTTPS']) && (($_SERVER['HTTPS'] == 'on') || ($_SERVER['HTTPS'] == '1'))) || (isset($_SERVER['HTTPS']) && (isset($_SERVER['SERVER_PORT']) && $_SERVER['SERVER_PORT'] == 443))) { $_SERVER['HTTPS'] = true; } elseif (!empty($_SERVER['HTTP_X_FORWARDED_PROTO']) && $_SERVER['HTTP_X_FORWARDED_PROTO'] == 'https' || !empty($_SERVER['HTTP_X_FORWARDED_SSL']) && $_SERVER['HTTP_X_FORWARDED_SSL'] == 'on') { $_SERVER['HTTPS'] = true; } else { $_SERVER['HTTPS'] = false; }
Recommended related articles:
Code implementation of the construction method and destructor method in php
How to implement counting sorting code in PHP
The above is the detailed content of Summary of commonly used functions and global variables in PHP (recommended). 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

How to optimize the lazy loading effect of images through PHP functions? With the development of the Internet, the number of images in web pages is increasing, which puts pressure on page loading speed. In order to improve user experience and reduce loading time, we can use image lazy loading technology. Lazy loading of images can delay the loading of images. Images are only loaded when the user scrolls to the visible area, which can reduce the loading time of the page and improve the user experience. When writing PHP web pages, we can optimize the lazy loading effect of images by writing some functions. Details below

How to reduce memory usage through PHP functions. In development, memory usage is a very important consideration. If a large amount of memory is used in a program, it may cause slowdowns or even program crashes. Therefore, reasonably managing and reducing memory usage is an issue that every PHP developer should pay attention to. This article will introduce some methods to reduce memory usage through PHP functions, and provide specific code examples for readers' reference. Use the unset() function to release variables in PHP. When a variable is no longer needed, use

PHP function introduction—curl_multi_getcontent(): Get the content of a cURL session. In PHP development, we often need to request data from other servers through the network. And cURL (ClientURL) is a powerful PHP extension library used for network communication in PHP. cURL provides a series of functions, one of which is curl_multi_getcontent(), which is used to obtain the content of a cURL session.

PHPDeprecated: Functionereg_replace()isdeprecated-Solution When developing in PHP, we often encounter the problem of some functions being declared deprecated. This means that in the latest PHP versions, these functions may be removed or replaced. One common example is the ereg_replace() function. ereg_replace

PHP image processing functions are a set of functions specifically used to process and edit images. They provide developers with rich image processing functions. Through these functions, developers can implement operations such as cropping, scaling, rotating, and adding watermarks to images to meet different image processing needs. First, I will introduce how to use PHP image processing functions to achieve image cropping function. PHP provides the imagecrop() function, which can be used to crop images. By passing the coordinates and size of the cropping area, we can crop the image

PHP functions have similarities with functions in other languages, but also have some unique features. Syntactically, PHP functions are declared with function, JavaScript is declared with function, and Python is declared with def. In terms of parameters and return values, PHP functions accept parameters and return a value. JavaScript and Python also have similar functions, but the syntax is different. In terms of scope, functions in PHP, JavaScript and Python all have global or local scope. Global functions can be accessed from anywhere, and local functions can only be accessed within their declaration scope.

PHP function introduction: strtr() function In PHP programming, the strtr() function is a very useful string replacement function. It is used to replace specified characters or strings in a string with other characters or strings. This article will introduce the usage of strtr() function and give some specific code examples. The basic syntax of the strtr() function is as follows: strtr(string$str, array$replace) where $str is the original word to be replaced.

The performance of different PHP functions is crucial to application efficiency. Functions with better performance include echo and print, while functions such as str_replace, array_merge, and file_get_contents have slower performance. For example, the str_replace function is used to replace strings and has moderate performance, while the sprintf function is used to format strings. Performance analysis shows that it only takes 0.05 milliseconds to execute one example, proving that the function performs well. Therefore, using functions wisely can lead to faster and more efficient applications.
