Regular match Just Once (no repetition)

Question

I faced this little regex problem (flags: Global)

[-+*&|]

It must match, for example, + in this expression, but not ++ or -:

12 + 47 - i++ / --foo

However, it fits all of these.

I am aware of this solution, but it is ugly (needs to be repeated three times):

[^-+*&|][-+*&|][^-+*&|]

Or perhaps

(?<![-+*&|])([-+*&|])(?![-+*&|])

Any better (shorter and more readable) solution?

+3

MightyPork 03 Aug At 9:05 am

2 answers

Ganonside · Answer 1 · 2014-08-06T13:06:52+0000

this seems a little more readable to me, but not much.

(?<![\+\-\*/\&\|])(?P<operator>[\+\-\*/\&\|])(?!(?P=operator))

matches:

+ ++ - -- * ** / // & && | ||
^    ^    ^    ^    ^    ^

Stephane Rolland · Answer 2 · 2014-08-06T13:08:56+0000

[-+*&|]{1,3}

you can use {min,max}

to determine the minimum and maximum number of occurrences.