c# - Trying to restrict subsequent same character occurrences -

c# - Trying to restrict subsequent same character occurrences -

i trying implement similar functionality of alter directory (cd) in command prompt.

the restriction that, 1 . directory names must contain alphabets. 2 . root directory "/" 3 . parent directory ".." 4 . path separator "/"

the input new path name .

input might . 1. directory name alone. - valid 2. directory/directory/directory - valid 3. directory//directory - invalid 4. .. - valid 5. directory/.. - valid 6. directory/... - invalid

and other combinations that.

to avoid complexity tried split check

to check input must contain letters, used ^[a-za-z]+$ this. but don't know how restrict / , dot(.) characters subsequent occurences 1 , 2 respectively

thanks

you can utilize string.indexof , check against it's homecoming value.

var is_only_one_slash = input.indexof("\\\\") == -1; var is_only_two_dots = input.indexof("..") > -1; if(is_only_one_slash && is_only_two_dots) { // valid }

c# regex