CODEWITHSUNDEEP
regex
Newbie
Newbie

Reputation: 167

regular expression with If condition question

I have the following regular expressions that extract everything after first two alphabets

^[A-Za-z]{2})(\w+)($) $2

now I want to the extract nothing if the data doesn't start with alphabets.

Example:

AA123   -> 123
123     -> ""

Can this be accomplished by regex?

Upvotes: 0

Views: 1199

Answers (2)

The fourth bird
The fourth bird

Reputation: 163362

Your pattern already captures 1 or more word characters after matching 2 uppercase chars. The $ does not have to be in a group, and this $2 should not be in the pattern.

^[A-Za-z]{2})(\w+)$

See a regex demo.

Another option could be a pattern with a conditional, capturing data in group 2 only if group 1 exist.

 ^([A-Z]{2})?(?(1)(\w+)|.+)$
  • ^ Start of string
  • ([A-Z]{2})? Capture 2 uppercase chars in optional group 1
  • (? Conditional
    • (1)(\w+) If we have group 1, capture 1+ word chars in group 2
    • | Or
    • .+ Match the whole line with at least 1 char to not match an empty string
  • ) Close conditional
  • $ End of string

Regex demo

For a match only, you could use other variations Using \K like ^[A-Za-z]{2}\K\w+$ or with a lookbehind assertion (?<=^[A-Za-z]{2})\w+$

Upvotes: 0

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 626845

Introduce an alternative to match any one or more chars from start to end of string if your regex does not match:

^(?:([A-Za-z]{2})(\w+)|.+)$

See the regex demo. Details:

  • ^ - start of string
  • (?: - start of a container non-capturing group:
    • ([A-Za-z]{2})(\w+) - Group 1: two ASCII letters, Group 2: one or more word chars
    • | - or
    • .+ - one or more chars other than line break chars, as many as possible (use [\w\W]+ to match any chars including line break chars)
  • ) - end of a container non-capturing group
  • $ - end of string.

Upvotes: 1

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