Python Regex to find a string in double quotes within a string

Question

I'm looking for a code in python using regex that can perform something like this

Input: Regex should return "String 1" or "String 2" or "String3"

Output: String 1,String2,String3

I tried r'"*"'

Answer 1

Here's all you need to do:

def doit(text):         import re   matches = re.findall(r'"(.+?)"',text)   # matches is now ['String 1', 'String 2', 'String3']   return ",".join(matches)  doit('Regex should return "String 1" or "String 2" or "String3" ') 

result:

'String 1,String 2,String3' 

As pointed out by Li-aung Yip:

To elaborate, .+? is the "non-greedy" version of .+. It makes the regular expression match the smallest number of characters it can instead of the most characters it can. The greedy version, .+, will give String 1" or "String 2" or "String 3; the non-greedy version .+? gives String 1, String 2, String 3.

In addition, if you want to accept empty strings, change .+ to .*. Star * means zero or more while plus + means at least one.

Answer 2

The highly up-voted answer doesn't account for the possibility that the double-quoted string might contain one or more double-quote characters (properly escaped, of course). To handle this situation, the regex needs to accumulate characters one-by-one with a positive lookahead assertion stating that the current character is not a double-quote character that is not preceded by a backslash (which requires a negative lookbehind assertion):

"(?:(?:(?!(?<!\\)").)*)" 

See Regex Demo

import re import ast   def doit(text):     matches=re.findall(r'"(?:(?:(?!(?<!\\)").)*)"',text)     for match in matches:         print(match, '=>', ast.literal_eval(match))   doit('Regex should return "String 1" or "String 2" or "String3" and "\\"double quoted string\\"" ') 

Prints:

"String 1" => String 1 "String 2" => String 2 "String3" => String3 "\"double quoted string\"" => "double quoted string"