can't create \footnote because of math

Question

I have this piece in the document:

Affymetrix-anotation-file\footnote{HG-U133_Plus_2.na32.annot.csv}

now I get an error because of the "Plus" in the footnote. Obviously Latex thinks, this is an math command. How can I solve this type of error?

thx for help

Answer 1

It should be the underscore that leads to error.

You can use \_ instead of _.

Affymetrix-anotation-file\footnote{HG-U133\_Plus\_2.na32.annot.csv}

Answer 2

You can also use \urldef from the url package.

\usepackage{url}
\urldef\foo{\url{HG-U133_Plus_2.na32.annot.csv}}

Then in the footnote:

\footnote{\foo}