Hi vineet2004,

One quick way is to use the "?" modifier like so: 

    while (<>) {
        # Only require a non-null first capture
        if (/(\w\w)(\w\w)?(\w\w)?(\w\w)?/) {
            # Do something
        }
    }

[download]

In each of the captures, the "?" says that the item is optional.  Therefore, the match will succeed if only the first capture succeeds.

Note that if you use warnings, you will still need to test each of the captures for null when you use them, to avoid getting uninitialized value warnings.

Update:  bart's comment below about the whitespace is a good one.  I think my solution will still work if you modify it slightly: 

    if (/(\s*\w\w)(\s+\w\w)?(\s+\w\w)?(\s+\w\w)?/) {
        # Do something
    }

[download]

Come to think of it, though, that just makes the whitespace part of the match, so ++bart, as his solution looks like a better one to do what you need.

s''(q.S:$/9=(T1';s;(..)(..);$..=substr+crypt($1,$2),2,3;eg;print$..$/

In reply to Re: pattern matching by liverpole
in thread pattern matching by vineet2004

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