Question

I am trying to match a semi dynamically generated string. So I can see if its the correct format, then extract the information from it that I need. My Problem is I no matter how hard I try to grasp regex can’t fathom it for the life of me. Even with the help of so called generators.

What I have is a couple different strings like the following. [@img:1234567890] and [@user:1234567890] and [@file:file_name-with.ext]. Strings like this pass through are intent on passing through a filter so they can be replaced with links, and or more readable names. But again try as I might I can’t come up with a regex for any given one of them.

I am looking for the format: [@word:] of which I will strip the [, ], @, and word from the string so I can then turn around an query my DB accordingly for whatever it is and work with it accordingly. Just the regex bit is holding me back.

Answer 1

Not sure what you mean by generators. I always use online matchers to see that my test cases work. @Virendra almost had it except forgot to escape the [] charaters.

/\[@(\w+):(.*)\]/

You need to start and end with a regex delimeter, in this case the ‘/’ character.

Then we escape the ‘[]’ which is use by regex to match ranges of characters hence the ‘[‘.

Next we match a literal ‘@’ symbol.

Now we want to save this next match so we can use it later so we surround it with ().

\w matches a word. Basically any characters that aren’t spaces, punctuation, or line characters.

Again match a literal :.

Maybe useful to have the second part in a match group as well so (.*) will match any character any number of times, and save it for you.

Then we escape the closing ] as we did earlier.

Since it sounds like you want to use the matches later in a query we can use preg_match to save the matches to an array.

$pattern = '/\[@(\w+):(.*)\]/';
$subject = '[@user:1234567890]';
preg_match($pattern, $subject, $matches);
print_r($matches);

Would output

array(
    [0] => '[@user:1234567890]', // Full match
    [1] => 'user', // First match
    [2] => '1234567890' // Second match
)

An especially helpful tool I’ve found is txt2re