When to use -, – and —? [duplicate]

Question

Possible Duplicate:
When should I use an em-dash, an en-dash, and a hyphen?

This is about hyphens (-), en-dashes (–) and em-dashes (—).

When to use which one? To be honest, I always use em-dashes unless I join words with a hyphen, but I never use an en-dash.

Answer 1

Hyphens are used in compound modifiers.

• a well-trained professional
• over-the-counter drugs

En dashes are used in place of "to" to connect numbers or words.

• The London–Amsterdam flight is delayed.
• The meeting is from 3:00–4:30 p.m.

Em dashes help set off amplifying or explanatory statements.

• The vampire—it had been awake half the night—flew out of its coffin.