regex check for white space in middle of string

Question

I want to validate that the characters are alpha numeric:

Regex aNum = Regex(\"[a-z][A-Z][0-9]\");

I want to add the option that there migh

Answer 1

Exactly two words with single space:

Regex aNum = Regex("[a-zA-Z0-9]+[\s][a-zA-Z0-9]+");

OR any number of words having any number of spaces:

Regex aNum = Regex("[a-zA-Z0-9\s]");