PHP Regex Not Matching Desired Substrings - php

Question

I've written the next regular expression
$pattern = "~\d+[.][\s]*[A-Z]{1}[A-Za-z0-9\s-']+~";
in order to match substrings as 2.bon jovi - it's my life
the problem is the only part that is recognized is - bon jovi
none " - " or " ' " are recognized by this regular expression.
I'd prefer to know what is wrong with the regular expression that I've wrote rather than getting a new one.

Answer 1

Your regular expressions states that after the period character (can be changed to \.), you will have zero or more white space characters which should then be followed by 1 upper case letter. In your string, you do not have any upper case letters.
Secondly, the - should be placed last when you want to match it. So, changing your regex to this: ~\d+[.][\s]*[A-Z]{1}[A-Za-z0-9\s'-]+~ will match something like so: 2.Bon jovi - it's my life.
On the other hand, you can change it to this: ~\d+[.][\s]*[A-Za-z0-9\s'-]+~ to match something like so: 2.bon jovi - it's my life.
EDIT: Ammended as per the comments of Marko D and aleation.

Answer 2

A better regular expression to handle that would be...
$pattern = "~\d+\.\s*[\pL\pP\s]+~";
CodePad.
This will match a number, followed by a ., followed by optional whitespace, followed by one or more Unicode letters, whitespace or punctuation marks.

Answer 3

$pattern = "~\d+\..*~";
$string = "2.bon jovi - it's my life";
preg_match($pattern, $string, $match);
print_r($match);
output: Array ( [0] => 2.bon jovi - it's my life )

Answer 4

So the way I understand this regular expression is:
\d+ // Match any digit, 1 or more times
[.] // Match a dot
[\s]* // Match 0 or more whitespace characters
[A-Z]{1} // Match characters between an UPPERCASE A-Z Range 1 time
[A-Za-z0-9\s-']+ // Match characters between A-Z, a-z, 0-9, whitespace, dashe and apostrophe
So straight away, your 'bon jovi' might not get matched as it's lower case and you're only looking for uppercase characters. 'bon jovi' also contains a space so perhaps changing that part of the regular expression to allow for lowercase characters and whitespace might help so you'd end up with:
$pattern = "~\d+[.][\s]*[A-Za-z\s]{1}[A-Za-z0-9\s-']+~";
Note: I quickly tested this on RegExr ( http://gskinner.com/RegExr/ ) and it appeared to match the string fine.

Answer 5

Your regrex is as follows.
~ // delimiter
\d+ // 1 or more numbers
[.] // a period
[\s]* // 0 or more whitespace characters
[A-Z]{1} // 1 upper case letter
[A-Za-z0-9\s-\']+ // 1 or more characters, from the character class
~ //delimiter
Comparing that to the string "2.bon jovi" You have:
~ //
\d+ // "2"
[.] // "."
[\s]* // ""
[A-Z]{1} // <- NO MATCH
[A-Za-z0-9\s-\']+ //
~ //
"bon" does not start with a captial letter, it therefore does not match [A-Z]{1}
Cleaner regex
There are a few simple things you can do to clean up your regex
don't use character-classes for one character
don't specify {1} it's the same as not being present
Applying the above to your existing regex you get:
$pattern = "~\d+\.\s*[A-Z][A-Za-z0-9\s-']+~";
Which is slightly easier to read.

Answer 6

Your [A-Z]{1} sub-pattern requires one capital letter, so "2.bon jovi - it's my life" will not match.
And you need to escape the - in the [A-Za-z0-9\s-'] character class, or put it at the start or end, otherwise it is specifying a range.
"~\d+\.[A-Za-z0-9\s'-]+~"
As pointed out in the comments, it is actually not necessary to escape the - in the character class in your regex. That is only because you happened to precede it with a metacharacter \s that cannot be part of a range. Normally, if you want to match a literal - and you have it in a character class, you must escape it or position it as described above.