validation problem

[bil_joe21]

I was wondering if there any preg_match condition that can validate -blahblah, 'b lahblah, bl.ahblah, .blahblah, blahblah- as an invalid input.
But take blah-blah, b'lahblah, blah blah, blahblah., bl. lahblah as a valid input.

Many thanks for the reply...

[xblue]

try to say exactly what you want, and you are halfway there already.

like, you want to allow letters at any position in the string, hyphens, apostrophs and spaces only in the middle, and the dot in the middle or at the end (which is roughly how I interpret your examples).

then you look at it again, but from left to right:
the first character may be ...
a sequence of characters may follow that may consist of ...
the last character may be ...

and put this together in a regular expression.