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
– Amarghosh

2009-11-25 12:39:38 +00:00
Commented Nov 25, 2009 at 12:39 — Amarghosh
– Amarghosh, Commented Nov 25, 2009 at 12:39

David M · Accepted Answer · 2009-11-25 12:43:00Z

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, 2009 at 12:43

answered Nov 25, 2009 at 12:37

David M

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3 Comments

Tim Pietzcker Over a year ago

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 Over a year ago

@Fabien: \s contains tabs, too.

Fabien Ménager Over a year ago

@Tim: yep, \s should be " ", sorry.

Amarghosh · Accepted Answer · 2009-11-25 12:46:36Z

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, 2009 at 12:46

Amarghosh

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2 Comments

David M Over a year ago

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.

Amarghosh Over a year ago

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.

Mikael S · Accepted Answer · 2009-11-25 12:39:16Z

1

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 +-]+$";

answered Nov 25, 2009 at 12:39

Mikael S

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Comments

user187291 · Accepted Answer · 2009-11-25 13:35:11Z

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.

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