php preg_match get numbers between two strings - php

Question

Hi I'm starting to learn php regex and have the following problem:
I need to extract the numbers inside $string.
The regex I use returns "NULL".
$string = 'Clasificación</a> (2194) </li>';
$regex = '/Clasificación</a>((.*?))</li>/';
preg_match($regex , $string, $match);
var_dump($match);
Thanks in advance.

Answer 1

There are three problems with your regex:
You aren't escaping the forward slash. You're using the forward slash as a delimiter, so if you want to use it as a literal character inside the expression, you need to escape it
((.*?)) doesn't do what you think it does. It creates two capturing groups -- one nested inside the other. I assume, you're trying to capture what's inside the parentheses. For that, you'll need to escape the ( and ) characters. The expression would become: \((.*?)\)
Your expression doesn't handle whitespace. In the string you've given, there is whitespace between the </a> and the beginning of the number -- </a> (2194). To ignore the whitespace and capture just the number, you need to use \s (which matches any whitespace character). For that, you need to write \s*\((.*?)\)\s*.
The final regular expression after fixing all the above errors, will look like:
$regex = '~Clasificación</a>\s*\((.*?)\)\s*</li>~';
Full code:
$string = 'Clasificación</a> (2194) </li>';
$regex = '~Clasificación</a>\s*\((.*?)\)\s*</li>~';
preg_match($regex , $string, $match);
var_dump($match);
Output:
array(2) {
[0]=>
string(32) "Clasificación (2194) "
[1]=>
string(4) "2194"
}
Demo.

Answer 2

You forget to espace / in your regex, since you're using the / as a delimiter:
$regex = '/Clasificación<\/a>((.*?))<\/li>/';
// ^ delimiter ^^ ^ delimiter
// ^^ / in a string which is escaped
Another way can be to change that delimiter, and then you will not have to escape it:
$regex = '#Clasificación<\/a>((.*?))<\/li>#';
See the PHP documentation for more information.

Answer 3

you will have to escape out the special characters that you want to match:
$regex = '/Clasificación<\/a> \((.*?)\) <\/li>/'
and may want to make your match a little more specific where it matters (depending on your use case)
$regex = '/Clasificación<\/a>\s*\(([0-9]+)\)\s*<\/li>/';
that will allow for 0 or more spaces before or after the (1234) and only match if there are only numbers in the ()
I just tried this in php:
php > preg_match($regex , $string, $match);
php > var_dump($match);
array(2) {
[0]=>
string(30) "Clasificacin</a> (2194) </li>"
[1]=>
string(4) "2194"
}