Regular Expression That Checks If A Number Is Prime

Re:Regular Expression That Checks If A Number Is Prime by Normal_gaussian on Friday September 09, 2016 @03:19AM (#12460192)

http://sed.sourceforge.net/sedfaq3.html

> Grouping and backreferences: All versions of sed support grouping and backreferences on the LHS and backreferences only on the RHS.

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Re:Regular Expression That Checks If A Number Is Prime by dllthomas on Friday September 09, 2016 @11:56AM (#12463377)

I saw that. I wasn't sufficiently confident as to whether it meant "all historical versions" or just "all current versions."

If the former, then it predated perl by quite a bit, of course.

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Re:Regular Expression That Checks If A Number Is Prime by btilly on Monday September 12, 2016 @12:18PM (#12480984)

Perl started with Henry Spenser's regular expression library, which was written in the mid-1980s. That got used in a lot of places, and may have been used in sed. It includes backreferences. I don't know what predates that.

Perl used that as a starting place and began adding extensions such as the difference between .* and .*?.

So using "non-regular thing" as a regular expression predates Perl. But the dialect we standardized on with the features people now expect is due to Perl's influence.

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Re:Regular Expression That Checks If A Number Is Prime by Normal_gaussian on Friday September 09, 2016 @03:14PM (#12465250)

Ah I get you.

I've tried finding some source for early versions but all the links I've found are dead. It's an interesting question!

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