Perl regexp / (\ r \ n | \ r | \ n) /

Question

I want to know how this ambiguous pattern is solved in perl (in general, everything that libpcre uses):

/(\r\n|\r|\n)/

When the pattern sees \r\n, will it match once or twice? And what are the rules facing this situation?

thank

Answer 1

It will match \r\nonce since Perl uses a regex engine that looks forward to change. See here .

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Answer 2

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Answer 3

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Answer 4

He will match him once. More details here: http://technocage.com/~caskey/dos2unix/