But people struggle with this. I distinctly remembering practicing this in class when prepping for matura (Slovenian version of SATs) so I guess it isn't inherently obvious to everyone.
In English, Em-dashes have a couple of different uses, but in the most common use they are usually set closed (no spaces on either end), though some styles set them with a space on either end. En-dashes have one use (similar to that of em-dashes, which is used varies by house style) where they are usually set open, and a number where they are usually set closed.
Given that the rules for these marks aren't particularly consistent, or even fixed, in English, I think its safe to say they aren't consistent for the same piece of punctuation across all uses in all Indo-European languages.
Actually, the en dash has more than one use: http://cddc.uchicago.edu/qanda/data/faq/topics/HyphensEnDash...
";" is surrounded by space left and right
":" has no space on the left in English, but it has one in French> Modern style guides recommend no space before them and one space after.
And that's really interesting about French. Personally I think a colon surrounded by spaces looks funny, but then again, I've never learned a language where that wasn't the correct way.
edit: my French girlfriend says French puts spaces on both sides of all punctuation except commas and periods. Like this !
Weirdos O.o
http://www.lemonde.fr/football/article/2014/09/17/ligue-des-...
Looks like it's indeed like she told you.
More often than not it's a dead giveaway...
(Another fun pedantic remark: French typography rules require that you apply the rules of a foreign language whenever you quote text in that language, so that the English rules should be respected for English quotations within a French text.)
And I agree with akx -- being French, I've seen my share of French people writing in English with the French rules, and I always thought that it could be used as an indicator by a careful reader.
(As an example, there used to be an ads campaign in the Parisian subway some years ago which advertised "I speak Wall Street English !" or something or the kind. As this was for an English class, I always found it funny that they couldn't get their English typography right.)