Forgive me, but what do you mean by a “dash.” All the examples here show two hyphens. These are not dashes. There are three types of dashes, namely Hyphens, Em Dashes and En Dashes The hyphen is the shortest of the three and is used most

Sorry to be so long, but I have been looking for a good comprehensive internet source on dashes; all the information seems to be in bits and pieces, and some of it is quite contradictory. Here is a good excerpt, however, from the Get it Write

All I can say is that I'm influenced by the ... the m-dash for the sentence as rewritten by Michael, above. But isn't everything in a sentence related by thought? Well, yeah, but the dash for the sentence we were discussing really served