How do I use lookahead assertion to limit by range the number of “/”
I have tired the following
^(?=/{1,3})$
but it doesn’t work
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How do I use lookahead assertion to limit by range the number of “/”
I have tired the following
^(?=/{1,3})$
but it doesn’t work
The easiest solution is to use a negative lookahead:
That basically means the string cannot contain 4 slashes.
This assumes you allow other characters between slashes, but a maximum of 3 slashes.
A positive version would be
^(?=[^/]*(?:/[^/]*){0,3}$)or^[^/]*(?:/[^/]*){0,3}$, without the lookahead.Of course, the problem is trivial without regular expressions, if possible.
Lets try to break that last one down:
^– Start of the string.[^/]*– Some characters that are not slashes (or none)(?: )– A logical group. Similar to(), but does not capture the result (we do not need it after validation)/[^/]*– Slash, followed by non-slash characters.{0,3}– From 0 to 3 times.$– End of the string.