The hyphen is usually a normal character in regular expressions. Only if it’s in a character class and between two other characters does it take a special meaning.
Thus:
[-]
matches a hyphen.[abc-]
matchesa
,b
,c
or a hyphen.[-abc]
matchesa
,b
,c
or a hyphen.[ab-d]
matchesa
,b
,c
ord
(only here the hyphen denotes a character range).