Regular Expression Match only first character

Question

I have this Regular Expression:

^([^6]*)6

I want it to match ONLY the first character and make sure its a 6. E.g.

60123456789

It should return 1 match

0123456789 should return 0 matches

How can I do this?

Currently the results it returns in my application is: 601234567890 returns an error

EDIT: This is a data annotation above my ViewModel property

[RegularExpression("^([^6]*)6", ErrorMessage = "Phone Numbers must start with a 6")]

what should it return when it matches with a `6`? The complete number ... ? — trk, Aug 06 '19 at 04:44
@Acidic When I enter more numbers, the error appears. It should return nothing when it matches with 6. If the first character isn't a 6, then the error should appear. — JianYA, Aug 06 '19 at 04:45
I tried @guijob's solution and Acidic's solution and they both work the same way. If there is a 6 at the start of the input and nothing else, the error doesn't show. If I add more characters, the error appears. — JianYA, Aug 06 '19 at 04:52
How does `^(?=6)` works same way than `[^\d](6\d+)`? `^(?=6)` returns an empty match when first char is 6 and `[^\d](6\d+)` matches all numbers after 6 if 6 is first number found, not necessary in first position — guijob, Aug 06 '19 at 04:59
The desired behaviour is this. The page loads and the input box already has a 6 in it. Then the user has to enter their phone number. if the user removes the 6, the error should appear. — JianYA, Aug 06 '19 at 05:02
You just need `"^6.*$"`, no need for parentheses. If you must invalidate `6nc-ded and more ?@#@@` input use `"^6[0-9]*$"`. Do you want to allow `6dhe%$^$%` like input? — Wiktor Stribiżew, Aug 06 '19 at 06:41

score 0 · Accepted Answer · edited Aug 06 '19 at 04:48

0

I think this should work:

'6123'.match(/^6(.+)$/)[0]

Where, '6123': is any number. For numbers starting with 6 it will match else it would return null.

Let me know if that works.

edited Aug 06 '19 at 04:48

Ari Seyhun

answered Aug 06 '19 at 04:46

trk

Sorry how do I place this in the code in my question? The input is dynamic. – JianYA Aug 06 '19 at 04:47
@JianYA, is this a jquery plugin ? It should work if you used the following string : `"^6(.+)$"`. – trk Aug 06 '19 at 04:52
Its the .net core syntax – JianYA Aug 06 '19 at 05:02

1 Answers1