Capturing all operators, parentheses and numbers separately in "(3 + 44)* 5 / 7" with Regex

Question

For input string: st = "(3 + 44)* 5 / 7"

I'm looking to get the following result using only regex: ["(", "3", "+", "44", ")", "*", "5", "/", "7"]

Attempts:

1. >>> re.findall("[()\d+\-*/].?", st)
   ['(3', '+ ', '44', ')*', '5 ', '/ ', '7']
   

   But I need to capture the parentheses in '(3' and ')*' separately as well.

2. >>> re.findall("[()\d+\-*/]?", st)    
   ['(', '3', '', '+', '', '4', '4', ')', '*', '', '5', '', '/', '', '7', '']
   

   This gives tons of blank tokens.

Answer 1

You can't use multi-character constructs like \d+ in a character class.

So you can do it by brute force like this:

re.findall(r"\(|\)|\d+|-|\*|/", st)

Or you can use a character class for single-character tokens, alternated with other things:

re.findall(r"[()\-*/]|\d+", st)