[SOLVED] What does a square brace enclosed expression mean in a regex pattern?

What does a square brace enclosed expression mean in a regex pattern?

I am trying to search for some pattern in PHP with the help of preg_match. Search pattern is like this (but this is wrong):

    /[\d\s*-\s*\d\s*(usd|eur)]{1}/i

\d  starts with integer,
\s*  there can be any number of whitespaces,
- there must be exactly one minus sign
\s* there can be any number of whitespaces,
\d then must be integer
\s* there can be any number of whitespaces,
(usd|eur) any of the following words must be present but one
[\d\s*-\s*\d\s*(usd|eur)]{1} - in string there should be exactly one occurence

the above pattern does not work, what I am doing wrong? For testing:

<?php
    $pattern = '/[\d\s*-\s*\d\s*(usd|eur)]{1}/i';
    $query = '100-120 100-120';

    echo $pattern.'<br/>';
    echo $query.'<br/>';

    if(preg_match($pattern, $query))
        echo 'OK';
    else
        echo 'not OK!';
?>

Note: I am trying to pull out data like this:

The price of item is 100 - 120 usd in our market

Solution

[...] is a character class. It means "match any one of these characters". [abc] will match a,b, or c. It doesn't match the string "abc".

In addition:

{1} means "match the preceding expression one time". However, matching once is the default. There is no need to explicitly tell it to match one time.

\d matches a single numeric digit. Based on your example, you want \d+ - match a number made up of at least one digit.

Here is what your pattern should look like:

/\d+\s*-\s*\d+\s*(usd|eur)/i