What is a correct regex expression to match exactly "1/2" or "50%"?
Matches:
1/2 1/10 10/23 13/30 50% 2% No matches:
0/2 1/0 02/15 50 4 1/2% I've tried /^([0-9]+/[0-9]+)|([0-9]+%)$/ but without success. I need to get exact matches
2 Answers
My attempt: ^(([1-9][0-9]*/[1-9][0-9]*)(?!%))|((?<!/)([1-9][0-9]*%))$ - https://regex101.com/r/rHvyKR/1
If you don't want to allow for a single 0, then you can't use [0-9]+, you need to demand one character out of [1-9] first, and then [0-9]* optional after that. And I threw in a Negative Lookahead and a Negative Lookbehind, to exclude the edge cases.
4 Comments
jhnc
from the "exactly" and
^ and $ used in the question, I'm guessing that lines like 1/2abc and abc50% should not match but your regex does not exclude them (you need extra parentheses around the | or duplicate ^...$ around each case)
C3roe
@jhnc fair enough, also "exactly" of course stands and falls with the quality of the given examples. But in hindsight, I'm guessing our interpretation makes sense.
jhnc
ie. you have
ab|cd when you need a(b|c)d or abd|acd
Mike
@C3roe perfect solution, thanks a lot!
Assuming that the whitespace in your first "Matches" line is a typo, you could do:
^[1-9][0-9]*(%|/[1-9][0-9]*)$ It is not clear if 1/234, 345/6, 78900%, etc, should match. I've assumed that they should. Note that excluding the second example (two numbers separated by slash, where first number is not smaller than second) is a bit complicated with basic regex syntax.
1 Comment
jhnc
I've just read @DuesserBaest's comment in full and noticed I've come up with effectively the same regex
^[1-9][0-9]*(?:%|\/[1-9][0-9]*)$/1\/2|50%/