Finding Parenthesis via Regular Expression

Regular Expression for matching parentheses

Two options:

Firstly, you can escape it using a backslash -- \(

Alternatively, since it's a single character, you can put it in a character class, where it doesn't need to be escaped -- [(]

How to search a string with parentheses using regular expression?

There are 12 characters with special meanings, you escape to its literal meaning with \ in front of it.

re.search(r'Ab\(123\)',string)

# or re.findall(r'Ab\(123\)',string)

Look up https://regex101.com/r/1bb8oz/1 for detail.

Regular expression to match balanced parentheses

Regular expressions are the wrong tool for the job because you are dealing with nested structures, i.e. recursion.

But there is a simple algorithm to do this, which I described in more detail in this answer to a previous question. The gist is to write code which scans through the string keeping a counter of the open parentheses which have not yet been matched by a closing parenthesis. When that counter returns to zero, then you know you've reached the final closing parenthesis.

RegEx to match stuff between parentheses

You need to make your regex pattern 'non-greedy' by adding a ? after the .+

By default, * and + are greedy in that they will match as long a string of chars as possible, ignoring any matches that might occur within the string.

Non-greedy makes the pattern only match the shortest possible match.

See Watch Out for The Greediness! for a better explanation.

Or alternately, change your regex to

\(([^\)]+)\)

which will match any grouping of parentheses that do not, themselves, contain parentheses.

Regex : Find a number between parentheses

This only matches 312312 in the first capture group:

^.*?\([^\d]*(\d+)[^\d]*\).*$

Regexplanation:

^        # Match the start of the line
.*?      # Non-greedy match anything
\(       # Upto the first opening bracket (escaped)
[^\d]*   # Match anything not a digit (zero or more)
(\d+)    # Match a digit string (one or more)
[^\d]*   # Match anything not a digit (zero or more)
\)       # Match closing bracket
.*       # Match the rest of the line
$        # Match the end of the line

See it here.

Regular Expression to get a string between parentheses in Javascript

You need to create a set of escaped (with \) parentheses (that match the parentheses) and a group of regular parentheses that create your capturing group:

var regExp = /\(([^)]+)\)/;var matches = regExp.exec("I expect five hundred dollars ($500).");
//matches[1] contains the value between the parenthesesconsole.log(matches[1]);

Finding Characters Between Parentheses with Regular Expression

Your regex is trying to match as many characters as it can before it stops at a ) character. There are three ) characters in your string, but starting at b the regex cannot match the third ) because there is a ( between b and the third ), and the ( doesn't fit the pattern between the [ ] brackets. But your regex can (and does) use the second ) to match the ) in its pattern.

Note that on the page you linked to, the answer from which you got this regexp specifically says it will not work when the parentheses are nested inside each other.

You can force the regexp to match the first ) rather than the second if you write the regexp so:

\(([^()]+)\)

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