Question

I need a regex to match a word that starts with #.

I wrote this question How to match a pound (#) symbol in a regex in php (for hashtags), but I forgot to explain that I need the # at the beginning of a word.

I need to match #word, #123, #12_sdas, but not 1#234 or #1234.

For example, in "#match1 notMatch not#Match #match2 notMatch #match3", only #match1, #match2 and #match3 should appear.

Edit: I just want one pound (#), followed by one or more [a-ZA-Z0-9_]. The match can’t have any of [a-ZA-Z0-9_] before.

My problem was finding the pound at the beginning of the word.

Answer 1

Try this:

preg_match_all('/(?:^|\s+)(#\w+)/', $your_input, $your_results);
// print results
print_r($your_results);

It will match all words beginning with a # symbol. Words can be sepearted by all valid whitespace characters (so one of \t\r\n\v\f)

Example

//input
#match1 notMatch not#Match #match2 notMatch #match3
//output
Array
(
    [0] => Array
        (
            [0] => #match1
            [1] =>  #match2
            [2] =>  #match3
        )

    [1] => Array
        (
            [0] => #match1
            [1] => #match2
            [2] => #match3
        )

)