Why should I use -​- in pages field of a BibTeX entry?

Question

In most BibTeX entries I found on the internet a page range in the page field is separated by a double hyphen --. Why should I use a double dash and not a single one -?

@misc{blub,
title="blah",
pages="1--99" <---
}

and not

@misc{blub,
title="blah",
pages="1-99" <---
}

Answer 1

The correct symbol for a range of numbers is an en-dash, which in LaTeX is usually input as --. Many BibTeX style files (.bst) files will do a search and replace, so that - is replaced by -- in the output (.bbl file). However, you can't be 100% sure that any given style will do this. So by putting -- in the .bib file, you make sure that you get the correct output whatever the style does.