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regexregex-group

Regex to allow special only between alpha numeric

I need a REGEX which should validate only if a string starts and ends with Alphabets or numbers and should allow below special characters in between them as below:

/*
hello  -> pass
what -> pass
how @@are you -> pass
how are you? -> pass
hi5kjjv  -> pass
8ask -> pass
yyyy. -> fail
! dff -> fail
NoSpeci@@@alcharacters -> pass
Q54445566.00 -> pass
q!Q1 -> pass
!Q1 -> fail
q!! -> fail
#NO -> fail
0.2Version -> pass
-0.2Version -> fail
*/

the rex works fine for above query but the issue is it expects at least two valid characters:

^[A-Za-z0-9]+[ A-Za-z0-9_@./#&+$%_=;?\'\,\!-]*[A-Za-z0-9]+

failing in case if we pass:

a -> failed but valid
1 -> failed but valid

I tried replacing + with * but this was accepting special characters from the start (@john) which is wrong.

[A-Za-z0-9]+  with [A-Za-z0-9]*
Solution

  • You may use this regex:

    ^[A-Za-z0-9](?:[! #$%;&'+,./=?@\w-]*[A-Za-z0-9?])?$

    Or if your regex flavor supports atomic groups then use a bit more efficient:

    ^[A-Za-z0-9](?>[! #$%;&'+,./=?@\w-]*[A-Za-z0-9?])?$

    RegEx Demo

    RegEx Details:

    • ^: Start
    • [A-Za-z0-9]: Match an alphanumeric character
    • (?>[! #$%;&'+,./=?@\w-]*[A-Za-z0-9?])?: Optional atomic group to match 0 or more of a specified char in [...] followed by an alphanumeric or ? characters
    • $: End