正则表达式匹配括号或括号内的字符串中的数字

Question

I have a dataset where each line contains a number that is enclosed within a set of parenthesis or brackets. eg

Jim Bob Smith [1975] 
Joe Bob Public (1955)

What I'm having problems with is creating a regex expression that will match the number (without the brackets or parenthesis) that will work under both conditions.

I've tried

(?<=\[).+?(?=\]) and
(?<=\().+?(?=\))

So I need help finding a way to combine the two. Any assistance would be greatly appreciated.

Answer 1

You may use the following .NET regex:

(?:(\()|\[)(.*?)(?(1)\)|])

See the regex demo

Details

• (?:(\\()|\\[) - a non-capturing group that matches and captures into Group 1 a ( char, else just matches a [ char
• (.*?) - Group 2: any 0 or more chars other than a newline char, as few as possible (instead of .*? , you might want to use \\d+ there to match 1 or more digits, or \\d{4} to match just four digits exactly, or even (?:20|19)\\d{2} to match a year in the 20th and 21st c.)
• (?(1)\\)|]) - a conditional construct : if Group 1 was matched, a ) is matched, else, a ] char.

Answer 2

Try

.*?[[(](\d{4})[])]

See here

1. .*? - non greedy any char
2. [[(] for either opening quote
3. (\\d{4}) - creates the 4 digit capture group you want.
4. [])] for either closing quote