I refuse to care about this. A single dash is all I will ever use. I see no possible reason to use the other two.
replies(13):
It's not like you can reliably write these consistently by hand either without going over the top in length to make it extremely obvious.
-5--2°C
post-war-pre-digital era
See sections 10-O-15-Q
Try Our New York-London Flight Connection!
-5—2
That looks like dogshit.
It's a mistake in the first place to decide to use only dashes and no spaces to convey all of this lol
-5 - 2 (Everyone knows a sign has no space - if you are building your sign for idiots try some of these:)
-5 > 2 -5->2 -5 <-> 2 -5 to 2 -5...2 Between -5 and 2
blah blah blah