I have this task: sum all numbers in string and perform multiplication
input: "3 chairs, 2 tables, 2*3 forks" result: 11
I already have regular expression to do this:
eval(str.match(/(\d[\d\.\*]*)/g).join(' + '))
But I want to add option to ignore numbers inside brackets "()"
input: "2 chairs, 3 tables (1 broke)" result: 5
How to do it?
Regular expressions were always pain for me :(
One simple way is to do a first pass and remove all parenthesized expressions.
str = str.replace(/\([^\)]*\)/g, "");
// now run your original algorithm to sum/multiply...
// ...
This is not super efficient but it does the job.
I should note that this does not handle nested parentheses, but it doesn't seem like that is required here.
You can use indexOf() and lastIndexOf() to detect the out-most parenthesis so that you can get rid of what you want.This works with indefinite parenthesis
"2 (not 3) and 3 (not 4)". You would actually need a stack or something similar to keep track of the left parens seen so far, popping whenever you see a right paren.(?=(\d+[\d.*]*)(?![^(]*?\)))\1
(?=( starts capturing a group using a look forward
(\d+[\d.*]*)
is the capture group for your number
(?![^(]*?\))
is a negative forward lookup that makes sure there isn't an open parenthesis after the number
)\1
look forward ends here match the found number.
