Problem with regular expression!

Question

I have used the following pattern for the regular expression for the phone number

pattern="[0-9 -+]+$";

The phone number may contain numbers, hyphen(-), space and plus(+). It works when i use numbers only. When numbers and alphabets are used it does not work.

What can be the problem, please do let me know.

Thanks in advance

So `9++23++-13` is a valid phone number? – Amarghosh Nov 25 '09 at 12:39 — Amarghosh, Nov 25 '09 at 12:39

David M · Answer 1 · 2009-11-25T12:43:00.613

7

It is interpreting the - as part of a range. try this:

pattern="^[0-9 +-]+$";

The - either needs escaping (\-) or moving to the end like this (thanks Tim).

edited Nov 25 '09 at 12:43

answered Nov 25 '09 at 12:37

David M

71,481
13
158
186

I edited the answer a bit: The + doesn't need to be escaped, and neither does the - if you put it at the beginning or end of the character class. – Tim Pietzcker Nov 25 '09 at 12:40
1

@Fabien: `\s` contains tabs, too. – Tim Pietzcker Nov 25 '09 at 12:42
@Tim: yep, \s should be " ", sorry. – Fabien Ménager Nov 25 '09 at 12:47

score 4 · Answer 2 · answered Nov 25 '09 at 12:46

4

Your regex will fail even after making the correction suggested by David. Because it matches any combination of one or more numbers and +, -. For example, it matches 99++++--12

Here is a better version that matches numbers in the format 999-999-9999 with an optional leading country code in the format +9999 (two to four digits long)

(\+\d{2,4}\s*)?(\d{3})-(\d{3})-(\d{4})

answered Nov 25 '09 at 12:46

Amarghosh

58,710
11
92
121

Well, this won't match UK numbers unless you put hyphens in them in odd places. Correct international form for a London number, for example, would be +44 20 xxxx xxxx. – David M Nov 25 '09 at 17:49
Matching all locales is a difficult task (in India it is `+91 \d{10}`) - that's why I specifically said it matches 3+3+4 numbers. I was just pointing out the faults of `[0-9+-]` pattern. – Amarghosh Nov 25 '09 at 18:01

score 1 · Answer 3 · edited Nov 25 '09 at 13:35

It needs to start with a ^ and the - needs to be escaped with a \

pattern=/^[0-9 \-+]+$/;

It needs to start with a ^ as that is an anchor for the start of the string, if you didn't it would validate strings that started with anything, as long as they ended with a number, space, - or +

- needs to be escaped as it is a special character and has a meaning other than -. While + is a special character, and if you want to treat it as a + outside a class it needs to be escaped, when inside a class only ]^-\ need to be escaped.

So outside of a class escape

.^$|*+?()[{\

And inside escape:

]^-\

However, most implementations allow you to escape all 12 special characters inside classes without error, and they will only give an error if you escape a non special character, which means that this (Note the extra \ before the plus) will also work fine.

pattern="^[0-9 \-\+]+$"

I always find that using a regex tester makes things easier as it allows me to see mistakes.

score 1 · Answer 4 · answered Nov 25 '09 at 12:39

Since - (dash) is used as the range symbol inside brackets in regexp you need to either escape it, or place it last:

pattern="[0-9 \-+]+$";
// or
pattern="[0-9 +-]+$";

You might also want to begin the regexp with ^ to make sure the whole string matches it, not just the end:

pattern="^[0-9 +-]+$";

Problem with regular expression!

4 Answers4