java regex not operator not working properly

Question

(\d+(\.|\,|\\|\/|\-)\d+) I have a regex like this. I'm catching numbers like 15.12, 15/15 with this regex it works correctly. But when I get the inverse with the not operator, it doesn't exactly work properly. Regex with "not" operator. [^(\d+(\.|\,|\\|\/|\-)\d+)]

Let's take "15/12 tons/tonne" as the sample text. Here I expect it to find ton/ton, but it doesn't take the "/" character, it just takes tonton. What am I doing wrong ? How can I fix ?

Example;

15/13 48 km/h  ---> 48 km/h

13.12 ton.     ---> ton.

10,11 ,kwh     ---> ,kwh

9-7 .mm.       ---> .mm.

As seen in the example, I want to find everything except numbers(including whitespaces).

Not sure what you're trying to do here, or why you would expect ton/ton. Are you saying you want to find slashes, dots, commas etc but only with non-numeric characters surrounding them? And how should the space in the middle be interpreted? — Dawood ibn Kareem
– Dawood ibn Kareem, Commented Mar 21, 2022 at 18:56
I'm not exactly sure what you're going after, but post on your bolded example: ^\d+/\d+\s+(tons/tonne)$ — Ryan
– Ryan, Commented Mar 21, 2022 at 19:04
(\d+(\.|\,|\\|\/|\-)\d+) with this regex I can find 15/12 in 15/12 tone/ton sentence. I want to find the whitespace ton/tonne by inverting it. I don't want to find things like slash commas separately I want to find anything other than "number character number".@DawoodibnKareem — Özgür Utku
– Özgür Utku, Commented Mar 21, 2022 at 19:08
I want to find tone/ton in 15/12 tone/ton sentence. If the sentence was 15-12 abc-abc I would like to find abc-abc. I want to find anything other than "number character number".@Ryan — Özgür Utku
– Özgür Utku, Commented Mar 21, 2022 at 19:11

score 1 · Accepted Answer · 2022-03-21 19:08:31Z

1

[^(\d+(\.|\,|\\|\/|\-)\d+)] is not the inverse of (\d+(\.|\,|\\|\/|\-)\d+)

In regular expressions, anything between the brackets are considered a character set. The ^ is a special character when it's the first character in the set, with it meaning the inverse of the character set.

https://regex101.com/r/7gJANc/4

This is a good way to see exactly which characters are being matched (or not matched) by that pattern.

Last edit:

To find what you're looking for, you can invert each of the instances of \d to \D. \D means "not-digit".

(\D+(\.|\,|\\|\/|\-)\D+) is your pattern but with \D:

https://regex101.com/r/7gJANc/5

It matches tons/tonne

edited Mar 21, 2022 at 19:08

answered Mar 21, 2022 at 19:00

user12842282

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6 Comments

Özgür Utku Over a year ago

thanks for your answer. (\D+(\.|\,|\\|\/|\-)\D+) this expression won't work for "15/12 tons of tons" though. What should we do for this situation? I want it to work in both "15/12 tons of tons" and "15/12 tons/tons". actually i want everything except "number charceter number".

user12842282 Over a year ago

Here's a way (?:\d+[.,\\\/-]\d+)?(.*) , but depending on all of your use cases it may not work out. This captures your number/number pattern if it exists. Everything else is captured into group 1.

user12842282 Over a year ago

One note about that pattern, I modified (\.|\,|\\|\/|\-) from your pattern to be [.,\\\/-]. It ends up describing the same thing. The dot doesn't need the backslash within the character set to be interpreted as a literal dot, and the dash doesn't when it's not part of a range.

Özgür Utku Over a year ago

(?:\d+[.,\\\/-]\d+)?(.*) I guess I'll use that. I'm going to have to modify my code a bit but there doesn't seem to be any other solution. but it may not work depending on all your use cases. What situations could it be?

user12842282 Over a year ago

It depends on what all you're throwing at it. What I remind myself when working with regular expressions is this quote by Jamie Zawinski: "Some people, when confronted with a problem, think 'I know, I'll use regular expressions.' Now they have two problems."

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