Regex to enter a decimal number digit by digit - regex

I have a requirement where user can input only between 0.01 to 100.00 in a textbox. I am using regex to limit the data entered. However, I cannot enter a decimal point, like 95.83 in the regex. Can someone help me fix the below regex?
(^100([.]0{1,2})?)$|(^\d{1,2}([.]\d{1,2})?)$
if I copy paste the value, it passes. But unable to type a decimal point.
Please advice.
Link to regex tester: https://regex101.com/r/b2BF6A/1
Link to demo: https://stackblitz.com/edit/react-9h2xsy

The regex
You can use the following regex:
See regex in use here
^(?:(?:\d?[1-9]|[1-9]0)(?:\.\d{0,2})?|0{0,2}\.(?:\d?[1-9]|[1-9]0)|10{2}(?:\.0{0,2})?)$
How it works
^(?:...|...|...)$ this anchors the pattern to ensure it matches the entire string
^ assert position at the start of the line
(?:...|...|...) non-capture group - used to group multiple alternations
$ assert position at the end of the line
(?:\d?[1-9]|[1-9]0)(?:\.\d{0,2})? first option
(?:\d?[1-9]|[1-9]0) match either of the following
\d?[1-9] optionally match any digit, then match a digit in the range of 1 to 9
[1-9]0 match any digit between 1 and 9, followed by 0
(?:\.\d{0,2})? optionally match the following
\. this character . literally
\d{0,2} match any digit between 0 and 2 times
0{0,2}\.(?:\d?[1-9]|[1-9]0) second option
0{0,2} match 0 between 0 and 2 times
\. match this character . literally
(?:\d?[1-9]|[1-9]0) match either of the following options
\d?[1-9] optionally match any digit, then match a digit in the range of 1 to 9
[1-9]0 match any digit between 1 and 9, followed by 0
10{2}(?:\.0{0,2})? third option
10{2} match 100
(?:\.0{0,2})? optionally match ., followed by 0 between 0 and 2 times
How it works (in simpler terms)
With the above descriptions for each alternation, this is what they will match:
Any two-digit number other than 0 or 00, optionally followed by any two-digit decimal.
In terms of a range, it's 1.00-99.99 with:
Optional leading zero: 01.00-99.99
Optional decimal: 01-99, or 01.-99, or 01.0-01.99
Any two-digit decimal other than 0 or 00
In terms of a range, it's .01-.99 with:
Optional leading zeroes: 00.01-00.99 or 0.01-0.99
Literally 100, followed by optional decimals: 100, or 100., or 100.0, or 100.00
The code
RegExp vs /pattern/
In your code, you can use either of the following options (replacing pattern with the pattern above):
new RegExp('pattern')
/pattern/
The first option above uses a string literal. This means that you must escape the backslash characters in the string in order for the pattern to be properly read:
^(?:(?:\\d?[1-9]|[1-9]0)(?:\\.\\d{0,2})?|0{0,2}\\.(?:\\d?[1-9]|[1-9]0)|10{2}(?:\\.0{0,2})?)$
The second option above allows you to avoid this and use the regex as is.
Here's a fork of your code using the second option.
Usability Issues
Please note that you'll run into a couple of usability issues with your current method of tackling this:
The user cannot erase all the digits they've entered. So if the user enters 100, they can only erase 00 and the 1 will remain. One option to resolving this is to make the entire non-capture group (with the alternations) optional by adding a ? after it. Whilst this does solve that issue, you now need to keep two regular expression patterns - one for user input and the other for validation. Alternatively, you could just test if the input is an empty string to allow it (but not validate the form until the field is filled.
The user cannot enter a number beginning with .. This is because we don't allow the input of . to go through your validation steps. The same rule applies here as the previous point made. You can allow it though if the value is . explicitly or add a new alternation of |\.
Similarly to my last point, you'll run into the issue for .0 when a user is trying to write something like .01. Again here, you can run the same test.
Similarly again, 0 is not valid input - same applies here.
An change to the regex that covers these states (0, ., .0, 0., 0.0, 00.0 - but not .00 alternatives) is:
^(?:(?:\d?[1-9]?|[1-9]0)(?:\.\d{0,2})?|0{0,2}\.(?:\d?[1-9]?|[1-9]0)|10{2}(?:\.0{0,2})?)$
Better would be to create logic for these cases to match them with a separate regex:
^0{0,2}\.?0?$
Usability Fixes
With the changes above in mind, your function would become:
See code fork here
handleChange(e) {
console.log(e.target.value)
const r1 = /^(?:(?:\d?[1-9]|[1-9]0)(?:\.\d{0,2})?|0{0,2}\.(?:\d?[1-9]|[1-9]0)|10{2}(?:\.0{0,2})?)$/;
const r2 = /^0{0,2}\.?0?$/
if (r1.test(e.target.value)) {
this.setState({
[e.target.name]: e.target.value
});
} else if (r2.test(e.target.value)) {
// Value is invalid, but permitted for usability purposes
this.setState({
[e.target.name]: e.target.value
});
}
}
This now allows the user to input those values, but also allows us to invalidate them if the user tries to submit it.

Using the range 0.01 to 100.00 without padding is this (non-factored):
0\.(?:0[1-9]|[1-9]\d)|[1-9]\d?\.\d{2}|100\.00
Expanded
# 0.01 to 0.99
0 \.
(?:
0 [1-9]
| [1-9] \d
)
|
# 1.00 to 99.99
[1-9] \d? \.
\d{2}
|
# 100.00
100 \.
00
It can be made to have an optional cascade if incremental partial form
should be allowed.
That partial is shown here for the top regex range :
^(?:0(?:\.(?:(?:0[1-9]?)|[1-9]\d?)?)?|[1-9]\d?(?:\.\d{0,2})?|1(?:0(?:0(?:\.0{0,2})?)?)?)?$
The code line with stringed regex :
const newRegExp = new RegExp("^(?:0(?:\\.(?:(?:0[1-9]?)|[1-9]\\d?)?)?|[1-9]\\d?(?:\\.\\d{0,2})?|1(?:0(?:0(?:\\.0{0,2})?)?)?)?$");
_________________________
The regex 'partial' above requires the input to be blank or to start
with a digit. It also doesn't allow 1-9 with a preceding 0.
If that is all to be allowed, a simple mod is this :
^(?:0{0,2}(?:\.(?:(?:0[1-9]?)|[1-9]\d?)?)?|(?:[1-9]\d?|0[1-9])(?:\.\d{0,2})?|1(?:0(?:0(?:\.0{0,2})?)?)?)?$
which allows input like the following:
(It should be noted that doing this requires allowing the dot . as
a valid input but could be converted to 0. on the fly to be put
inside the input box.)
.1
00.01
09.90
01.
01.11
00.1
00
.
Stringed version :
"^(?:0{0,2}(?:\\.(?:(?:0[1-9]?)|[1-9]\\d?)?)?|(?:[1-9]\\d?|0[1-9])(?:\\.\\d{0,2})?|1(?:0(?:0(?:\\.0{0,2})?)?)?)?$"

Related

How to create a matching regex pattern for "greater than 10-000-000 and lower than 150-000-000"?

I'm trying to make
09-546-943
fail in the below regex pattern.
​^[0-9]{2,3}[- ]{0,1}[0-9]{3}[- ]{0,1}[0-9]{3}$
Passing criteria is
greater than 10-000-000 or 010-000-000 and
less than 150-000-000
The tried example "09-546-943" passes. This should be a fail.
Any idea how to create a regex that makes this example a fail instead of a pass?
You may use
^(?:(?:0?[1-9][0-9]|1[0-4][0-9])-[0-9]{3}-[0-9]{3}|150-000-000)$
See the regex demo.
The pattern is partially generated with this online number range regex generator, I set the min number to 10 and max to 150, then merged the branches that match 1-8 and 9 (the tool does a bad job here), added 0? to the two digit numbers to match an optional leading 0 and -[0-9]{3}-[0-9]{3} for 10-149 part and -000-000 for 150.
See the regex graph:
Details
^ - start of string
(?: - start of a container non-capturing group making the anchors apply to both alternatives:
(?:0?[1-9][0-9]|1[0-4][0-9]) - an optional 0 and then a number from 10 to 99 or 1 followed with a digit from 0 to 4 and then any digit (100 to 149)
-[0-9]{3}-[0-9]{3} - a hyphen and three digits repeated twice (=(?:-[0-9]{3}){2})
| - or
150-000-000 - a 150-000-000 value
) - end of the non-capturing group
$ - end of string.
This expression or maybe a slightly modified version of which might work:
^[1][0-4][0-9]-[0-9]{3}-[0-9]{3}$|^[1][0]-[0-9]{3}-[0-9]{2}[1-9]$
It would also fail 10-000-000 and 150-000-000.
In this demo, the expression is explained, if you might be interested.
This pattern:
((0?[1-9])|(1[0-4]))[0-9]-[0-9]{3}-[0-9]{3}
matches the range from (0)10-000-000 to 149-999-999 inclusive. To keep the regex simple, you may need to handle the extremes ((0)10-000-000 and 150-000-000) separately - depending on your need of them to be included or excluded.
Test here.
This regex:
((0?[1-9])|(1[0-4]))[0-9][- ]?[0-9]{3}[- ]?[0-9]{3}
accepts (space) or nothing instead of -.
Test here.

Visual Basic - RegEx - Overall Length Check regardless the number of matches

I have the following problem :
This is my RegEx-Pattern :
\d*[a-z A-Z][a-zA-Z0-9 _?!()\/\\]*
It allows anything but numbers that stand alone like : 1 , 11 , 111 or so on.
My question : How can I set the overall Length of the input regardless of the matches ?
i tried it with several options like {1,30} before each match and i put the regex in a group with ( ) and then {1,30} but it still doesnt work.
If anyone could help me i would appreciate it :).
Allowed string:
Group1
Group 1
1Group
Group!?()\/
Group !()\?!
a1 a1 a1 a1
Not Allowed:
1
11
And so on. {1,30} after a match restricts the number of how many times i can input the match. What i want to know is: How can i set the maximum length of my above RegEx, like after 30 chars the input is reached regardless of the matches?
In order to disallow a numeric string input only, you can use a negative look-ahead (?!\d+$) and to set a limit to the input, use a limiting quantifier {1,30}:
(?!\d+$)[a-zA-Z0-9 _?!()\/\\]{1,30}
See demo
Note that if you plan to match whole strings, you'd need anchors: ^ at the beginning will anchor the regex to the beginning of string, and $ will anchor at the end.
^(?!\d+$)[a-zA-Z0-9 _?!()\/\\]{1,30}$
See another demo

Regex failing to match number and dash with letter (or space and letter)

In the tester this works ... but not in PostgreSQL.
My data is like this -- usually a series of letters, followed by 2 numbers and a POSSIBLE '-' or 'space' with only ONE letter following. I am trying to isolate the 2 numbers and the Possible '-" or 'space' AND the ONE letter with my regex:
For ex:
AJ 50-R Busboys ## should return 50-R
APPLES 30 F ## should return 30 F
FOOBAR 30 Apple ## should return 30
Regex's (that have worked in the tester, but not in PostgreSQL) that I've tried:
substring(REF from '([0-9]+)-?([:space:])?([A-Za-z])?')
&
substring(REF from '([0-9]+)-?([A-Za-z])?')
So far everything tests out in the tester...but not the PostgreSQL. I just keep getting the numbers returns -- AND NOTHING AFTER IT.
What I am getting now(for ex):
AJ 50-R Busboys ## returns as "50" NOT as "50-R"
Your looking for: substring(REF from '([0-9]+(-| )([A-Za-z]\y)?)')
In SQLFiddle. Your primary problem is that substring returns the first or outermost matching group (ie., pattern surrounded with ()), which is why you get 50 for your '50-R'. If you were to surround the entire pattern with (), this would give you '50-R'. However, the pattern you have fails to return what you want on the other strings, even after accounting for this issue, so I had to modify the entire regex.
This matches your description and examples.
Your description is slightly ambiguous. Leading letters are followed by a space and then two digits in your examples, as opposed to your description.
SELECT t, substring(t, '^[[:alpha:] ]+(\d\d(:?[\s-]?[[:alpha:]]\M)?)')
FROM (
VALUES
('AJ 50-R Busboys') -- should return: 50-R
,('APPLES 30 F') -- should return: 30 F
,('FOOBAR 30 Apple') -- should return: 30
,('FOOBAR 30x Apple') -- should return: 30x
,('sadfgag30 D 66 X foo') -- should return: 30 D - not: 66 X
) r(t);
->SQLfiddle
Explanation
^ .. start of string (last row could fail without anchoring to start and global flag 'g'). Also: faster.
[[:alpha:] ]+ .. one or more letters or spaces (like in your examples).
( .. capturing parenthesis
\d\d .. two digits
(:? .. non-capturing parenthesis
[\s-]? .. '-' or 'white space' (character class), 0 or 1 times
[[:alpha:]] .. 1 letter
\M .. followed by end of word (can be end of string, too)
)? .. the pattern in non-capturing parentheses 0 or 1 times
Letters as defined by the character class alpha according to the current locale! The poor man's substitute [a-zA-Z] only works for basic ASCII letters and fails for anything more. Consider this simple demo:
SELECT substring('oö','[[:alpha:]]*')
,substring('oö','[a-zA-Z]*');
More about character classes in Postgres regular expressions in the manual.
It's because of the parentheses.
I've looked everywhere in the documentation and found an interesting sentence on this page:
[...] if the pattern contains any parentheses, the portion of the text that matched the first parenthesized subexpression (the one whose left parenthesis comes first) is returned.
I took your first expression:
([0-9]+)-?([:space:])?([A-Za-z])?
and wrapped it in parentheses:
(([0-9]+)-?([:space:])?([A-Za-z])?)
and it works fine (see SQLFiddle).
Update:
Also, because you're looking for - or space, you could rewrite your middle expression to [-|\s]? (thanks Matthew for pointing that out), which leads to the following possible REGEX:
(([0-9]+)[-|\s]?([A-Za-z])?)
(SQLFiddle)
Update 2:
While my answer provides the explanation as to why the result represented a partial match of your expression, the expression I presented above fails your third test case.
You should use the regex provided by Matthew in his answer.

Regex - Validation of numeric with up to 4 decimal places

I am having a bit of difficulty with the following:
I need to allow any positive numeric value up to four decimal places. Here are some examples.
Allowed:
123
12345.4
1212.56
8778787.567
123.5678
Not allowed:
-1
12.12345
-12.1234
I have tried the following:
^[0-9]{0,2}(\.[0-9]{1,4})?$|^(100)(\.[0]{1,4})?$
However this doesn't seem to work, e.g. 1000 is not allowed when it should be.
Any ideas would be greatly appreciated.
Thanks
To explain why your attempt is not working for a value of 1000, I'll break down the expression a little:
^[0-9]{0,2} # Match 0, 1, or 2 digits (can start with a zero)...
(\.[0-9]{1,4})?$ # ... optionally followed by (a decimal, then 1-4 digits)
| # -OR-
^(100) # Capture 100...
(\.[0]{1,4})?$ # ... optionally followed by (a decimal, then 1-4 ZEROS)
There is no room for 4 digits of any sort, much less 1000 (theres only room for a 0-2 digit number or the number 100)
^\d* # Match any number of digits (can start with a zero)
(\.\d{1,4})?$ # ...optionally followed by (a decimal and 1-4 digits)
This expression will pass any of the allowed examples and reject all of the Not Allowed examples as well, because you (and I) use the beginning-of-string assertion ^.
It will also pass these numbers:
.2378
1234567890
12374610237856987612364017826350947816290385
000000000000000000000.0
0
... as well as a completely blank line - which might or might not be desired
to make it reject something that starts with a zero, use this:
^(?!0\d)\d* # Match any number of digits (cannot "START" with a zero)
(\.\d{1,4})?$ # ...optionally followed by (a decimal and 1-4 digits)
This expression (which uses a negative lookahead) has these evaluations:
REJECTED Allowed
--------- -------
0000.1234 0.1234
0000 0
010 0.0
You could also test for a completely blank line in other ways, but if you wanted to reject it with the regex, use this:
^(?!0\d|$)\d*(\.\d{1,4})?$
Try this:
^[0-9]*(?:\.[0-9]{0,4})?$
Explanation: match only if starting with a digit (excluding negative numbers), optionally followed by (non-capturing group) a dot and 0-4 digits.
Edit: With this pattern .2134 would also be matched. To only allow 0 < x < 1 of format 0.2134, replace the first * with a + above.
This regex would do the trick:
^\d+(?:\.\d{1,4})?$
From the beginning of the string search for one or more digits. If there's a . it must be followed with atleast one digit but a maximum of 4.
^(?<!-)\+?\d+(\.?\d{0,4})?$
The will match something with doesn't start with -, maybe has a + followed by an integer part with at least one number and an optional floating part of maximum 4 numbers.
Note: Regex does not support scientific notation. If you want that too let me know in a comment.
Well asked!!
You can try this:
^([0-9]+[\.]?[0-9]?[0-9]?[0-9]?[0-9]?|[0-9]+)$
If you have a double value but it goes to more decimal format and you want to shorter it to 4 then !
double value = 12.3457652133
value =Double.parseDouble(new DecimalFormat("##.####").format(value));

RegEx: Uk Landlines, Mobile phone numbers

I've been struggling with finding a suitable solution :-
I need an regex expression that will match all UK phone numbers and mobile phones.
So far this one appears to cover most of the UK numbers:
^0\d{2,4}[ -]{1}[\d]{3}[\d -]{1}[\d -]{1}[\d]{1,4}$
However mobile numbers do not work with this regex expression or phone-numbers written in a single solid block such as 01234567890.
Could anyone help me create the required regex expression?
[\d -]{1}
is blatently incorrect: a digit OR a space OR a hyphen.
01000 123456
01000 is not a valid UK area code. 123456 is not a valid local number.
It is important that test data be real area codes and real number ranges.
^\s*(?(020[7,8]{1})?[ ]?[1-9]{1}[0-9{2}[ ]?[0-9]{4})|(0[1-8]{1}[0-9]{3})?[ ]?[1-9]{1}[0-9]{2}[ ]?[0-9]{3})\s*|[0-9]+[ ]?[0-9]+$
The above pattern is garbage for many different reasons.
[7,8] matches 7 or comma or 8. You don't need to match a comma.
London numbers also begin with 3 not just 7 or 8.
London 020 numbers aren't the only 2+8 format numbers; see also 023, 024, 028 and 029.
[1-9]{1} simplifies to [1-9]
[ ]? simplifies to \s?
Having found the intial 0 once, why keep searching for it again and again?
^(0....|0....|0....|0....)$ simplifies to ^0(....|....|....|....)$
Seriously. ([1]|[2]|[3]|[7]){1} simplifies to [1237] here.
UK phone numbers use a variety of formats: 2+8, 3+7, 3+6, 4+6, 4+5, 5+5, 5+4. Some users don't know which format goes with which number range and might use the wrong one on input. Let them do that; you're interested in the DIGITS.
Step 1: Check the input format looks valid
Make sure that the input looks like a UK phone number. Accept various dial prefixes, +44, 011 44, 00 44 with or without parentheses, hyphens or spaces; or national format with a leading 0. Let the user use any format they want for the remainder of the number: (020) 3555 7788 or 00 (44) 203 555 7788 or 02035-557-788 even if it is the wrong format for that particular number. Don't worry about unbalanced parentheses. The important part of the input is making sure it's the correct number of digits. Punctuation and spaces don't matter.
^\(?(?:(?:0(?:0|11)\)?[\s-]?\(?|\+)44\)?[\s-]?\(?(?:0\)?[\s-]?\(?)?|0)(?:\d{5}\)?[\s-]?\d{4,5}|\d{4}\)?[\s-]?(?:\d{5}|\d{3}[\s-]?\d{3})|\d{3}\)?[\s-]?\d{3}[\s-]?\d{3,4}|\d{2}\)?[\s-]?\d{4}[\s-]?\d{4}|8(?:00[\s-]?11[\s-]?11|45[\s-]?46[\s-]?4\d))(?:(?:[\s-]?(?:x|ext\.?\s?|\#)\d+)?)$
The above pattern matches optional opening parentheses, followed by 00 or 011 and optional closing parentheses, followed by an optional space or hyphen, followed by optional opening parentheses. Alternatively, the initial opening parentheses are followed by a literal + without a following space or hyphen. Any of the previous two options are then followed by 44 with optional closing parentheses, followed by optional space or hyphen, followed by optional 0 in optional parentheses, followed by optional space or hyphen, followed by optional opening parentheses (international format). Alternatively, the pattern matches optional initial opening parentheses followed by the 0 trunk code (national format).
The previous part is then followed by the NDC (area code) and the subscriber phone number in 2+8, 3+7, 3+6, 4+6, 4+5, 5+5 or 5+4 format with or without spaces and/or hyphens. This also includes provision for optional closing parentheses and/or optional space or hyphen after where the user thinks the area code ends and the local subscriber number begins. The pattern allows any format to be used with any GB number. The display format must be corrected by later logic if the wrong format for this number has been used by the user on input.
The pattern ends with an optional extension number arranged as an optional space or hyphen followed by x, ext and optional period, or #, followed by the extension number digits. The entire pattern does not bother to check for balanced parentheses as these will be removed from the number in the next step.
At this point you don't care whether the number begins 01 or 07 or something else. You don't care whether it's a valid area code. Later steps will deal with those issues.
Step 2: Extract the NSN so it can be checked in more detail for length and range
After checking the input looks like a GB telephone number using the pattern above, the next step is to extract the NSN part so that it can be checked in greater detail for validity and then formatted in the right way for the applicable number range.
^\(?(?:(?:0(?:0|11)\)?[\s-]?\(?|\+)(44)\)?[\s-]?\(?(?:0\)?[\s-]?\(?)?|0)([1-9]\d{1,4}\)?[\s\d-]+)(?:((?:x|ext\.?\s?|\#)\d+)?)$
Use the above pattern to extract the '44' from $1 to know that international format was used, otherwise assume national format if $1 is null.
Extract the optional extension number details from $3 and store them for later use.
Extract the NSN (including spaces, hyphens and parentheses) from $2.
Step 3: Validate the NSN
Remove the spaces, hyphens and parentheses from $2 and use further RegEx patterns to check the length and range and identify the number type.
These patterns will be much simpler, since they will not have to deal with various dial prefixes or country codes.
The pattern to match valid mobile numbers is therefore as simple as
^7([45789]\d{2}|624)\d{6}$
Premium rate is
^9[018]\d{8}$
There will be a number of other patterns for each number type: landlines, business rate, non-geographic, VoIP, etc.
By breaking the problem into several steps, a very wide range of input formats can be allowed, and the number range and length for the NSN checked in very great detail.
Step 4: Store the number
Once the NSN has been extracted and validated, store the number with country code and all the other digits with no spaces or punctuation, e.g. 442035557788.
Step 5: Format the number for display
Another set of simple rules can be used to format the number with the requisite +44 or 0 added at the beginning.
The rule for numbers beginning 03 is
^44(3\d{2})(\d{3])(\d{4})$
formatted as
0$1 $2 $3 or as +44 $1 $2 $3
and for numbers beginning 02 is
^44(2\d)(\d{4})(\d{4})$
formatted as
(0$1) $2 $3 or as +44 $1 $2 $3
The full list is quite long. I could copy and paste it all into this thread, but it would be hard to maintain that information in multiple places over time. For the present the complete list can be found at: http://aa-asterisk.org.uk/index.php/Regular_Expressions_for_Validating_and_Formatting_GB_Telephone_Numbers
Given that people sometimes write their numbers with spaces in random places, you might be better off ignoring the spaces all together - you could use a regex as simple as this then:
^0(\d ?){10}$
This matches:
01234567890
01234 234567
0121 3423 456
01213 423456
01000 123456
But it would also match:
01 2 3 4 5 6 7 8 9 0
So you may not like it, but it's certainly simpler.
Would this regex do?
// using System.Text.RegularExpressions;
/// <summary>
/// Regular expression built for C# on: Wed, Sep 8, 2010, 06:38:28
/// Using Expresso Version: 3.0.2766, http://www.ultrapico.com
///
/// A description of the regular expression:
///
/// [1]: A numbered capture group. [\+44], zero or one repetitions
/// \+44
/// Literal +
/// 44
/// [2]: A numbered capture group. [\s+], zero or one repetitions
/// Whitespace, one or more repetitions
/// [3]: A numbered capture group. [\(?]
/// Literal (, zero or one repetitions
/// [area_code]: A named capture group. [(\d{1,5}|\d{4}\s+?\d{1,2})]
/// [4]: A numbered capture group. [\d{1,5}|\d{4}\s+?\d{1,2}]
/// Select from 2 alternatives
/// Any digit, between 1 and 5 repetitions
/// \d{4}\s+?\d{1,2}
/// Any digit, exactly 4 repetitions
/// Whitespace, one or more repetitions, as few as possible
/// Any digit, between 1 and 2 repetitions
/// [5]: A numbered capture group. [\)?]
/// Literal ), zero or one repetitions
/// [6]: A numbered capture group. [\s+|-], zero or one repetitions
/// Select from 2 alternatives
/// Whitespace, one or more repetitions
/// -
/// [tel_no]: A named capture group. [(\d{1,4}(\s+|-)?\d{1,4}|(\d{6}))]
/// [7]: A numbered capture group. [\d{1,4}(\s+|-)?\d{1,4}|(\d{6})]
/// Select from 2 alternatives
/// \d{1,4}(\s+|-)?\d{1,4}
/// Any digit, between 1 and 4 repetitions
/// [8]: A numbered capture group. [\s+|-], zero or one repetitions
/// Select from 2 alternatives
/// Whitespace, one or more repetitions
/// -
/// Any digit, between 1 and 4 repetitions
/// [9]: A numbered capture group. [\d{6}]
/// Any digit, exactly 6 repetitions
///
///
/// </summary>
public Regex MyRegex = new Regex(
"(\\+44)?\r\n(\\s+)?\r\n(\\(?)\r\n(?<area_code>(\\d{1,5}|\\d{4}\\s+"+
"?\\d{1,2}))(\\)?)\r\n(\\s+|-)?\r\n(?<tel_no>\r\n(\\d{1,4}\r\n(\\s+|-"+
")?\\d{1,4}\r\n|(\\d{6})\r\n))",
RegexOptions.IgnoreCase
| RegexOptions.Singleline
| RegexOptions.ExplicitCapture
| RegexOptions.CultureInvariant
| RegexOptions.IgnorePatternWhitespace
| RegexOptions.Compiled
);
//// Replace the matched text in the InputText using the replacement pattern
// string result = MyRegex.Replace(InputText,MyRegexReplace);
//// Split the InputText wherever the regex matches
// string[] results = MyRegex.Split(InputText);
//// Capture the first Match, if any, in the InputText
// Match m = MyRegex.Match(InputText);
//// Capture all Matches in the InputText
// MatchCollection ms = MyRegex.Matches(InputText);
//// Test to see if there is a match in the InputText
// bool IsMatch = MyRegex.IsMatch(InputText);
//// Get the names of all the named and numbered capture groups
// string[] GroupNames = MyRegex.GetGroupNames();
//// Get the numbers of all the named and numbered capture groups
// int[] GroupNumbers = MyRegex.GetGroupNumbers();
Notice how the spaces and dashes are optional and can be part of it.. also it is now divided into two capture groups called area_code and tel_no to break it down and easier to extract.
Strip all whitespace and non-numeric characters and then do the test. It'll be musch , much easier than trying to account for all the possible options around brackets, spaces, etc.
Try the following:
#"^(([0]{1})|([\+][4]{2}))([1]|[2]|[3]|[7]){1}\d{8,9}$"
Starts with 0 or +44 (for international) - I;m sure you could add 0044 if you wanted.
It then has a 1, 2, 3 or 7.
It then has either 8 or 9 digits.
If you want to be even smarter, the following may be a useful reference: http://en.wikipedia.org/wiki/Telephone_numbers_in_the_United_Kingdom
It's not a single regex, but there's sample code from Braemoor Software that is simple to follow and fairly thorough.
The JS version is probably easiest to read. It strips out spaces and hyphens (which I realise you said you can't do) then applies a number of positive and negative regexp checks.
Start by stripping the non-numerics, excepting a + as the first character.
(Javascript)
var tel=document.getElementById("tel").value;
tel.substr(0,1).replace(/[^+0-9]/g,'')+tel.substr(1).replace(/[^0-9]/g,'')
The regex below allows, after the international indicator +, any combination of between 7 and 15 digits (the ITU maximum) UNLESS the code is +44 (UK). Otherwise if the string either begins with +44, +440 or 0, it is followed by 2 or 7 and then by nine of any digit, or it is followed by 1, then any digit except 0, then either seven or eight of any digit. (So 0203 is valid, 0703 is valid but 0103 is not valid). There is currently no such code as 025 (or in London 0205), but those could one day be allocated.
/(^\+(?!44)[0-9]{7,15}$)|(^(\+440?|0)(([27][0-9]{9}$)|(1[1-9][0-9]{7,8}$)))/
Its primary purpose is to identify a correct starting digit for a non-corporate number, followed by the correct number of digits to follow. It doesn't deduce if the subscriber's local number is 5, 6, 7 or 8 digits. It does not enforce the prohibition on initial '1' or '0' in the subscriber number, about which I can't find any information as to whether those old rules are still enforced. UK phone rules are not enforced on properly formatted international phone numbers from outside the UK.
After a long search for valid regexen to cover UK cases, I found that the best way (if you're using client side javascript) to validate UK phone numbers is to use libphonenumber-js along with custom config to reduce bundle size:
If you're using NodeJS, generate UK metadata by running:
npx libphonenumber-metadata-generator metadata.custom.json --countries GB --extended
then import and use the metadata with libphonenumber-js/core:
import { isValidPhoneNumber } from "libphonenumber-js/core";
import data from "./metadata.custom.json";
isValidPhoneNumber("01234567890", "GB", data);
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