\s is the single space ' ' character. In your set [ \t\n\r\f] that thing right before the \t is \s.

Oooh I see now... in a character set [\s\t\f\r\n], \s means a single space.
in a regex \s means all of the chars in this set: [\s\t\f\r\n]. Yep, confusing!!
\s has a context dependent meaning. Such as it is.

In reply to Re^4: About a piece of code by Marshall
in thread About a piece of code by trewq

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