Question

I have text like this (1 or 0 tab + multiple whitespaces at line beginning):

(tab)   There are a tab and 4 whitespaces before me.    // line 1
(tab)     There are a tab and 6 whitespaces before me.  // line 2
       There are 6 whitespaces before me.               // line 3
   There are 4 whitespaces before me.                   // line 4   

When i use ^[\t\s]\s*, only line 1,2 are matched, line 3, 4 are not matched, why?

(When i use ^\s*, line 3 and 4 can be matched.)

Thanks!

Answer 1

That is interesting. I’m not sure why the \s doesn’t work inside of [] brackets. Perhaps it is because [] defines explicit characters and \s is ambiguous (it can stand for multiple characters). In other words \s stands for any whitespace, including a tab(\t). However, if you explicitly specify a space in this case (^[\t ]\s*) it will work.