RegEx to match anything BUT decimal numbers with percent symbol

Question

I'm terrible at RegEx. Can anyone show a regex to use if I want to check a string for anything BUT digits 0-9, decimal point and percent sign?

I've tried this...

if (preg_match('/[^0-9.]+%/i',  $string)) {
     echo 'invalid';
}

but it's not working correctly. I have a input field which asks a user what the tax rate should be, and this is going to verify they have entered a VALID tax rate. I want them to enter it like "5.2%" rather than in decimal, and I will do the math on the back-end.

A VALID match would be "6%" or "5.2%" etc. A INVALID match would be "2" or "0.05" or "A"

You don't need `+` if you're just testing for existence of something. A single character match is enough. — Barmar, Nov 08 '16 at 17:45
@Barmar - I tried inside the brackets but it didn't seem to work there either — Phil, Nov 08 '16 at 17:46
Then you haven't explained what you want, because that should fix it. — Barmar, Nov 08 '16 at 17:46
Does the match have to be the whole string? Is `10 is 5% of 50` valid? — Barmar, Nov 08 '16 at 17:48
@Barmar - updated my question to give more insight into what I'm trying to do. — Phil, Nov 08 '16 at 17:50

score 2 · Accepted Answer · edited May 23 '17 at 12:19

2

Look for a valid match, then invert it in the test:

if (!preg_match('/[\d.]%/', $string) {
    echo 'invalid';
}

But since this is supposed to test the whole string, not just look for a percentage anywhere in it, you need to anchor it:

if (!preg_match('/^[\d.]+%$/', $string) {
    echo 'invalid';
}

Note that this will allow something like .%. You probably should use something like Regular expression to match numbers with or without commas and decimals in text to match the number part.

edited May 23 '17 at 12:19

Community

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answered Nov 08 '16 at 17:50

Barmar

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thank you - will accept as correct as soon as it lets me. – Phil Nov 08 '16 at 17:54
1

@anubhava No, that's why I suggested replacing `[\d.]` with the answer in that other question, because it should be invalid. – Barmar Nov 08 '16 at 18:04

score 1 · Answer 2 · answered Nov 08 '16 at 17:50

1

You can match valid input and reverse your if condition:

if (preg_match('/\b\d*\.?\d+%/',  $string) === FALSE) {
     echo 'invalid';
}

RegEx Demo

answered Nov 08 '16 at 17:50

anubhava

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thank you!!! Your post was very helpful but to be fair Barmar's suggestion works too and he was a minute sooner. Thank you though! – Phil Nov 08 '16 at 17:54
Of course, it is your prerogative to mark any answer but just for the fact, my answer was 5 sec faster :) – anubhava Nov 08 '16 at 18:09
1

I'm sorry I didn't realize that. How do I see the exact timestamp? – Phil Nov 08 '16 at 19:00
Just the mouse over "answered ... ago" text below the answers – anubhava Nov 08 '16 at 19:01
I see it now...I had no idea. Will be sure to check this in the future thank you! – Phil Nov 08 '16 at 20:18

RegEx to match anything BUT decimal numbers with percent symbol

2 Answers2