6

I'm interested in all the difference, that means:

  • appearance: If there are common rules across fonts like distance from baseline, length and so on.
  • typographical rules: If they are handled differently when the compiler chooses where to break lines/pages.
  • semantically: The meaning of them, that is also when I'm supposed to use them.

Googling it I've found that exist a lot of similar glyph, even if I never seen them in any LaTeX document. Some of them - all usable in text mode without external packages - are: \--, \---, \----, \textendash, \textemdash. So if you want to expand your answer you could also clarify what are those symbols and when they should be used.

gvgramazio
  • 2,660
  • 3
    The typographic rules for using these symbols vary by language. Which language, or languages, do you employ in your documents? – Mico Jun 02 '18 at 10:16
  • 2
    The common rules across fonts normally are that - (hyphen) is the shortest, followed by an en-dash --/\textenmdash (you'd expect it to be one en long, one en is half an em), the longest of the three is an em-dash ---/\textemdash (one em long, one em was traditionally the width of the capital M). See also https://en.wikipedia.org/wiki/Dash – moewe Jun 02 '18 at 10:24
  • 1
    In Latin modern the hyphen is visibly thicker and lower than en-dash and em-dash. In Linux Libertine the general tendency is the same, but less noticeable. With mathpazo all characters are roughly at the same height, but the hyphen is still a tad thicker. There is a difference between -- and \-- as well as --- and \---. You'll definitely want to have a look at https://tex.stackexchange.com/q/3819/35864 and https://tex.stackexchange.com/q/103608/35864. The semantics and common use depend on the language. – moewe Jun 02 '18 at 10:36
  • @Mico, usually English and Italian. – gvgramazio Jun 02 '18 at 14:24
  • @moewe, your comment could be an answer. Also, I think that you identified my question as a duplicate. I swear that I searched for an answer but I didn't get it, probably because - is a special character. – gvgramazio Jun 02 '18 at 14:26

1 Answers1

8
  • - generates a hyphen (aka ‘dash’)
  • -- generates an en-dash
  • --- generates an em-dash
  • $-$ generates a minus sign (in math mode)

A hyphen is the shortest, an em-dash is the longest.

  • Hyphens are used for compound words like ‘daughter-in-law’ and ‘X-ray’. Hyphens are also use to break up a long word at the end of a line within a paragraph.

  • En-dashes are used for number ranges like ‘pages 13–34’, and also in contexts like ‘exercise 1.2.6–52’.

  • Em-dashes are used for punctuation in sentences—they are what we often call simply dashes.

(The TeXbook, page 4)

In German I would use ~-- (a non-breaking space followed by an en-dash followed by a normal space) instead of --- as a dash.

I would assume that \textendash is equivalent to -- and \textemdash to ---.

\- is defined as \discretionary{-}{}{}. It generates a hyphen if it is at the end of a line or nothing otherwise. Please note that words containing a discretionary are ignored by TeX's automatic hyphenation algorithm. (The TeXbook, pages 95–96)

\--, \--- and \---- are not standard LaTeX. They appear to be defined by the extdash package, see this answer (thanks to moewe for the link in the comments).

jakun
  • 5,981
  • 3
    you might add joint-author references, as in "the Birch--Swinnerton-Dyer conjecture", to the uses for the en-dash (two authors there, Birch, and the already-hyphenated Swinnerton-Dyer). and you may as well add \- (the discretionary hyphen) just to be exhaustively complete. – barbara beeton Jun 02 '18 at 14:26