I am writing an applications where I want to:

1. remvoe extra spaces between words, i.e. "xxx yyy" becomes "xxx yyy" and that the input is only A-Z and 0-9 (i.e. no specail characters)

2. the input hast the format "xxx.yyy.ccc.etc) where "xxx", "yyy", "ccc", etc can only A-Z, 0-9, last character cannot be a period, and first character of "xxx", "yyy", "ccc", etc is A-Z.

My questions are how to best remove the extra spaces and how check that only A-Z and 0-9 are entered.

TIA