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# Need help matching and solving for numbers with exponents.

Posted on 2013-11-20
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I am looking for a pattern to match numbers from an expression that have exponents and are enclosed in ():
(64²xy)                                should match 64²
(6xy/-2²³xy)                        should match -2²³
(64²xy/2²yx)                       should match 64² and 2²
(6xy/-2²³+ab)                     should match -2²³
6xy/-2²³xy                          should not match anything as the expression is not enclosed in ()

The closest I have come to solving this is "([\-]?[0-9]+[°¹²³]+)".  This pattern matches all of the above example text but I only want it to match the first four examples.

Finally I would like to replace the matched text with a number that solves the exponent.
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Question by:NevSoFly
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LVL 35

Accepted Solution

Terry Woods earned 500 total points
ID: 39663930
The round brackets need escaping, otherwise they will be interpreted for their regular expression meaning (which is a group or lookahead, or lookbehind).

Also, given that with the third example you're trying to match 2 values within the string, it's important not to "consume" parts of the string for the first match such that the second match is missed. To achieve this, we need to use a lookahead.

This seems to work:
-?[0-9]+[°¹²³]+(?=[^(]*\))
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Author Comment

ID: 39664094
I tested your suggestion on gskinner.com/regexr but it didn't return any matches.
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LVL 35

Expert Comment

ID: 39664115
I tried it myself; the copy and paste of the pattern added a space character to the end, which broke it. Once I removed the space, it worked.
Also, in case it helps anyone else, the correct URL for the site's online tool is http://gskinner.com/RegExr/
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Author Closing Comment

ID: 39664123
Thanks, deleting that extra space made all the difference in the world.
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Author Comment

ID: 39664196
Sorry, I forgot about the second part of my question.   I would like to replace the matched text with a number that solves the exponent.
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LVL 35

Expert Comment

ID: 39664254
My specialty is regular expressions (I don't program in .NET) so you're probably best asking a separate question if you need help with that.
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