How to match 2 separate numbers in Javascript

Question

I have this regex that should match when there's two numbers in brackets /(P|C\(\d+\,{0,1}\s*\d+\))/g for example:

C(1, 2) or P(2 3) //expected to match

C(43) or C(43, ) // expect not to match

but it also matches the ones with only 1 number, how can i fix it?

The alternation (pipe character "|") in your regex matches a single P character OR the rest of the regex. I recommend replacing that part with a character class... [PC] — Aaron Cicali, Feb 16 '21 at 06:00

Nick · Answer 1 · 2021-02-16T06:19:28.300

You have a couple of issues. Firstly, your regex will match either P on its own or C followed by numbers in parentheses; you should replace P|C with [PC] (you could use (?:P|C) but [PC] is more performant, see this Q&A). Secondly, since your regex makes both the , and spaces optional, it can match 43 without an additional number (the 4 matches the first \d+ and the 3 the second \d+). You need to force the string to either include a , or at least one space between the numbers. You can do that with this regex:

[PC]\(\d+[ ,]\s*\d+\)

Demo on regex101

score 1 · Accepted Answer · answered Feb 16 '21 at 06:06

1

Try this regex

[PC]\(\d+(?:,| +) *\d+\)

Click for Demo

Explanation:

[PC]\( - matches either P( or C(
\d+ - matches 1+ digits
(?:,| +) - matches either a , or 1+ spaces
*\d+ - matches 0+ spaces followed by 1+ digits
\) - matches )

answered Feb 16 '21 at 06:06

Gurmanjot Singh

10,224
2
19
43

score 1 · Answer 3 · answered Feb 16 '21 at 06:20

You can relax the separator between the numbers by allowing any combination of command and space by using \d[,\s]+\d. Test case:

const regex = /[PC]\(\d+[,\s]+\d+\)/g;
[
  'C(1, 2) or P(2 3)',
  'C(43) or C(43, )'
].forEach(str => {
  let m = str.match(regex);
  console.log(str + ' ==> ' + JSON.stringify(m));
});

Output:

C(1, 2) or P(2 3) ==> ["C(1, 2)","P(2 3)"]
C(43) or C(43, ) ==> null

score 0 · Answer 4 · answered Feb 16 '21 at 06:27

Your regex should require the presence of at least one delimiting character between the numbers.

I suppose you want to get the numbers out of it separately, like in an array of numbers:

let tests = [
    "C(1, 2)",
    "P(2 3)",
    "C(43)",
    "C(43, )"
];

for (let test of tests) {
    console.log(
        test.match(/[PC]\((\d+)[,\s]+(\d+)\)/)?.slice(1)?.map(Number)
    );
}

How to match 2 separate numbers in Javascript

4 Answers4