Regex of number inside brackets - php

Question

I need to get the float number inside brackets..
I tried this '([0-9]*[.])?[0-9]+' but it returns the first number like 6 in the first example.
Also I tried this
'/\((\d+)\)/'
but it returns 0.
Please note that I need the extracted number either int or float.
Can u plz help

Answer 1

As you need to match bracket also, You need to add () in regular expression:
$str = 'Serving size 6 pieces (40)';
$str1 = 'Per bar (41.5)';
preg_match('#\(([0-9]*[.]?[0-9]+)\)#', $str, $matches);
print_r($matches);
preg_match('#\(([0-9]*[.]?[0-9]+)\)#', $str1, $matches);
print_r($matches);
Output:
Array
(
[0] => (40)
[1] => 40
)
Array
(
[0] => (41.5)
[1] => 41.5
)
DEMO

Answer 2

You could escape brackets:
$str = 'Serving size 6 pieces (41.5)';
if (preg_match('~\((\d+.?\d*)\)~', $str, $matches)) {
print_r($matches);
}
Outputs:
Array
(
[0] => (41.5)
[1] => 41.5
)
Regex:
\( # open bracket
( # capture group
\d+ # one or more numbers
.? # optional dot
\d* # optional numbers
) # end capture group
\) # close bracket
You could also use this to get only one digit after the dot:
'~\((\d+.?\d?)\)~'

Answer 3

You need to escape the brackets
preg_match('/\((\d+(?:\.\d+)?)\)/', $search, $matches);
explanation
\( escaped bracket to look for
( open subpattern
\d a number
+ one or more occurance of the character mentioned
( open Group
?: dont save data in a subpattern
\. escaped Point
\d a number
+ one or more occurance of the character mentioned
) close Group
? one or no occurance of the Group mentioned
) close subpattern
\) escaped closingbracket to look for
matches numbers like
1,
1.1,
11,
11.11,
111,
111.111 but NOT .1, .
https://regex101.com/r/ei7bIM/1

Answer 4

You could match an opening parenthesis, use \K to reset the starting point of the reported match and then match your value:
\(\K\d+(?:\.\d+)?(?=\))
That would match:
\( Match (
\K Reset the starting point of the reported match
\d+ Match one or more digits
(?: Non capturing group
\.\d+ Match a dot and one or more digits
)? Close non capturing group and make it optional
(?= Positive lookahead that asserts what follows is
\) Match )
) Close posive lookahead
Demo php