正则表达式允许-不超过2次

Question

i am using ^(^[az]?[a0-z9]+[.|-][a0-z9]+[az]+[.|-][a0-z9]+[az]?$)+$ , this force user type 2 hyphen(-) in his expression ....

But i need that regular expression can allow maximum 2 hypen and minimum one hyphen in his expression....

Answer 1

This is a simple re implementation.

/^[^-]+(-[^-]+){1,2}$/

And the test result:

"123".match(/^[^-]+(-[^-]+){1,2}$/)
null

"123-123".match(/^[^-]+(-[^-]+){1,2}$/)
["123-123", "-123"]

"123-123-123".match(/^[^-]+(-[^-]+){1,2}$/)
["123-123-123", "-123"]

"123-123-123-123".match(/^[^-]+(-[^-]+){1,2}$/)
null

And if you just copy one from other, then you should try to write one by yourself.
If not, you should delete it and restart.

Answer 2

^[^-]*-+[^-]*-{0,1}[^-]*$

String1: abc-pqr, String2: aaa-bbb, String3 aaa-bbb-ccc-ddd, where String 1 and 2 are valid and 3 is invalid?

This allows String 1 and 2. But not 3.

Answer 3

This regex should work...

/^[^-]*-[^-]*-[^-]*$/

It works by capturing anything except a hyphen (zero or more times), then a hyphen, then anything else again, then another hyphen, then anything else. It has a start and end marker to ensure that the whole string does not contain any more hyphens.

Breaks down like this...

/       # begin regex
^       # start of string
[^-]*   # not hyphen ([^-]), zero or more times (*)
-       # hyphen
[^-]*   # not hyphen ([^-]), zero or more times (*)
-       # hyphen
[^-]*   # not hyphen ([^-]), zero or more times (*)
$       # end of string
/       # end regex