The match string for a look behind match must match a fixed number of characters. That means that ?, *, + and {n, m} are not allowed because they can match a variable number of characters. It also means that if you use |, each clause must be the same length.

If you really, really must use a look behind to match the first a then you could:

$str =~ /(?<=^a)/;

[download]

but all you actually need is /a/.

Perl is environmentally friendly - it saves trees

In reply to Re: look-ahead and look behind!! by GrandFather
in thread look-ahead and look behind!! by narainhere

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