Nested parentheses get string one by one

Question

I have textbox and user write a formula and I get the text from textbox to split the parentheses .By the way I'm not trying to calculate formula I try to just get strings .I'm trying to get strings from nested parentheses Here is my code:

var txt = "((a-b)/month)/(c+d)";
var reg = /^\((.+)\)$/;
var newTxt = txt.split('(');
for (var i = 1; i < newTxt.length; i++) {
    var value = newTxt[i].split(')')[0];

    if (value == "") {
        value = txt.match(reg)[1];
    }
    console.log(value);
}

And my output is

   (a-b)/month)/(c+d
    a-b
    c+d

But I'm trying to get string between parentheses like

(a-b)/month
a-b
c+d

I'd consider using an expression parser instead, much easier in the long run. — Dave Newton, May 28 '15 at 13:50
I mean nested parentheses ( (..)....). Consider a string like this ((a+b)/c) and the the first string is (a+b)/c the second one is (a+b) — Murat Furkan Sönmez, May 28 '15 at 14:07

score 4 · Accepted Answer · answered May 28 '15 at 14:10

4

This is another way

    var a = [], r = [];
    var txt = "(((a-b)+(f-g))/month)/(c+d)";
    for(var i=0; i < txt.length; i++){
        if(txt.charAt(i) == '('){
            a.push(i);
        }
        if(txt.charAt(i) == ')'){
            r.push(txt.substring(a.pop()+1,i));
        }
    }    
    alert(r);

answered May 28 '15 at 14:10

Sujith

206
1
6

thats what im talking about. Thanks @Sujith – Murat Furkan Sönmez May 28 '15 at 14:27

James Newton · Answer 2 · 2015-05-28T14:16:51.143

This will capture the text in the outer parentheses, including the parentheses themselves:

(\((?>[^()]+|(?1))*\))

Output:

((a-b)/month)
(c+d)

Explanation:

( start first capturing group
\( opening parenthesis
(?> look behind to check that...
[^()]+ ... there are no parentheses ...
| ... or that...
(?1) ... there is a nested group that has already been captured by this expression (recursion)
\) closing parenthesis
) end of capturing group

Ah. Sorry. Your question is about JavaScript and JavaScript doesn't support look-behind.

Nested parentheses get string one by one

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