How many built-in functions does php have?

1. filter_var function

For example, used to verify whether the input text is an email address: filter_var('123456@qq.com',FILTER_VALIDATE_EMAIL ); the returned value is the result of matching the correct email address.

2. prase_url function

Parse the url and return each component

<?php
$url = &#39;https://www.baidu.com/web/http/index.html?a=add&b=bad&#39;;
print_r(parse_url($url));
echo parse_url($url, PHP_URL_PATH);
?>

The above result will be output:

Array ( [scheme] => https [host] => www.baidu.com [path] => /web/http/index.html [query] => a=add&b=bad ) 
/web/http/index.html

3. http_build_query

generates the request string after URL-encoding. After we filter the parameters passed by the url, we can pass these parameters into http_build_query() in the form of an array to build the query parameters. :

$url="https://www.baidu.com";
$data = array('foo'=>'bar',
              'baz'=>'boom',
              'cow'=>'milk',
              'php'=>'hypertext processor');
$query=http_build_query($data);
$uri=$url.'?'.$query;
echo $uri;
?>

4, $_SERVER

$_SERVER is a server that contains header information (header), path (path), and script locations (script locations), etc. Array of information.

The more commonly used ones are:

$_SERVER['REMOTE_ADDR']: The IP address of the user browsing the current page.

$_SERVER['HTTP_HOST']: The content of the Host: item in the current request header, if it exists.

$_SERVER['SERVER_ADDR']: The IP address of the server where the script is currently running.

$_SERVER['REQUEST_TIME_FLOAT']: The timestamp when the request starts, microsecond level accuracy. Effective since PHP 5.4.0.

$_SERVER[SERVER_NAME']: The host name of the server where the script is currently running. If the script is running on a virtual host, the name is determined by the value set for that virtual host.

Recommended tutorial: PHP video tutorial

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