Regex to validate relative path with single / or ending with /-CodePudding

I'm trying to compose a regex which checks the validity of a relative path. It should start with a / and if it has anything following it, it must also end with another /.

Examples:

/ => valid
// => not valid
/abc => not valid
/abc/ => valid

I'm using the following at the moment which responds correctly for all cases except the single /: "^\/[ A-Za-z0-9_\/] \/"

Do I need a lookahead?

CodePudding user response：

I believe the following would work:

^\/(?:[^/\n] \/)*$

See the online demo. You could match whichever characters you'd want to allow for inside the character class, but the above would mean:

^\/ - Start-line anchor and a escaped forward slash;
(?:[^/\n] \/)* - A non-capturing, 1 negated characters '/' or a newline, followed by an escaped forward slash, matched 0 times;
$ - End-line anchor.