How to view regular matching results through PHP's own server, _PHP tutorial

How to view the regular matching results through the server that comes with PHP.

As we all know, PHP code requires a web server to execute. To test PHP code, you must build a web server. This brings more inconvenience to our daily study. Fortunately, after PHP v5.4, PHP will come with a web server with simple functions.

Start the built-in web server

First, go to the custom web folder and start the built-in web server:

cd ~/public_html
php -S localhost:8000

Port number 8000 is customized and can be replaced with other unused ports.

After startup, the control interface is as follows:

Test the built-in server

Create test.php in the public_html folder,

<&#63;php
phpinfo();
&#63;>

Then visit localhost:8000/test.php in the browser, you should be able to see the php information page:

Regular matching
Let’s take a look at a simple example of regular matching in PHP:

<&#63;php
$subject = 'abc3def';
$pattern = '/c\dde/';
preg_match($pattern, $subject, $matches, PREG_OFFSET_CAPTURE);
print_r($matches);
&#63;>

You can view the running results through PHP's built-in web server. If nothing else, you can see the following output,

Array
(
  [0] => Array
  (
    [0] => c3de
    [1] => 2
  )
)

Next let’s analyze this code carefully.

preg_match function

The prototype of the preg_match function is int preg_match ( string $pattern , string $subject [, array &$matches [, int $flags = 0 [, int $offset = 0 ]]] ). Among them, pattern is the regular expression, subject is the string to be matched, and the following are optional parameters. PREG_OFFSET_CAPTURE in the code is the flags value. Its function is to output the offset of the matching result to the matches variable together with the matching result. By default, only the matching result is output to matches. For detailed description of this function, please refer to the preg_match official documentation.

Regular expression

The ‘/cdef/’ in the code is a regular expression. In most programs, regular expressions are placed between two forward slashes. d means matching numbers, so the regular expression in the code matches the string of c number def. For more syntax of regular expressions, you can refer to the 30-minute introductory tutorial on regular expressions. By the way, a pattern modifier can be added after the second slash of the regular expression. The simplest pattern modifier is i, which ignores case when matching. For example, the regular expression /def/ will fail when matching the string abcDef, while /def/i will succeed when matching the string abcDef. For more pattern modifiers, see Pattern Modifiers.

print_r function

The print_r function prints easy-to-understand information about a variable. Unlike print and echo, which can only print ordinary variables such as strings and integers, print_r can also print array variables and object variables and output them in an easy-to-understand format. Let’s expand on this. There is another function in PHP that is often used to print information, which is the var_dump function. As the name of the function suggests, this function is often used under debugging. In addition to printing the value of a variable, it can also print the type of the variable.

Articles you may be interested in:

• Collection of the most commonly used PHP regular expressions
• Detailed explanation of the operating modes of various web servers based on PHP

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