How do you determine, using RegExp, whether or not a substring is between parentheses?-CodePudding

Might be a duplicate; I thought this question had to have been already asked, but I searched and couldn’t find one.

How do you determine, using RegExp, whether or not a substring is between parentheses?

Say I want to check if the text “fox” is surrounded by parentheses in the following sentence:

The (quick) brown fox jumps (over) the lazy dog.

I tried this RegEx, but it tests true when “fox” is actually not parenthesized but does have parentheses to its left and right:

\(.*?fox.*?\)

I tried it with negative lookbehind and negative lookahead, and it doesn’t work either:

\(.*?(?<!\)).*?fox.*?(?!\().*?\)

CodePudding user response：

Here's a way to guaranteed that the word exists in inner parentheses only without existing in something nested:

\([^()]*fox[^()]*\)

\( - Open

[^()]* - 0 or more of any character that isn't parentheses

fox - fox

[^()]* - repeat pattern

\) - Close

CodePudding user response：

This will match any term in parenthesis:

\(.*?\)

The (quick) brown fox jumps (over) the lazy dog.

This question mark will ensure that the regex is 'lazy' and will only match the first instance of a closing parenthesis.

Removing the question mark like this: \(.*\) will give you the following match, which is probably not what you want:

The (quick) brown fox jumps (over) the lazy dog.

If you literally only want to match "(fox)", then the correct regex is:

\(fox\)

You can use an online regex tester or text editor to answer these kind of questions.