I have some regex that selects the first 6 characters and last six characters. ^.{0,6} .{6}$.

I basically only want it to select the first/last 6 characters if there are 12 characters.

Eg. select nothing if 202203, but select the first six characters if 202201202203.

Is there any way to accomplish this?

Thanks

CodePudding user response：

Your pattern ^.{0,6} .{6}$ matches 0-6 characters with this part .{0,6} and matches a mandatory space before the last 6 characters which is not present in 202201202203

You can use 2 capture group instead, and then you can select if you want the first or last 6 characters.

^(.{6})(.{6})$

Regex demo

Note that the . can also match a space.

CodePudding user response：

This works if 12 characters is your minimum and maximum by using look ahead:

^.{6}(?=.{6}).{6}$