hash-tag in \href causes error

Question

I'm creating a beamer presentation. I want to put a link to a source which has a hash-tag in it (#). When I try to compile this I get an error:

! Illegal parameter number in definition of \test.
<to be read again> 
                   }
l.91 \end{itemize}
                   % ends low level
? x

This is the line I'm using:

\href{http://highered.mcgrew-hill.com/classware/ala.do?isbn=0072956208&alaid=ala_1500202&showSelfStudyTree=true#}{source}

Is there a way around this?

Answer 1

Be careful to escape the hash character #:

\href{http://example.com/ala.do?foo=bar&showSelfStudyTree=true\#}{source} % # truncated

I have to admit that in this case (hash at the very end of the link), this achieves successful compilation, but the hash character is lost upon opening the link from my pdf-viewer (evince). If the hash is somewhere inside the link, it is preserved:

\href{http://example.com/ala.do?showSelfStudyTree=true\#&foo=bar}{source} % # perserved

Answer 2

I created a normal article (not a beamer presentation), and for some reasons could not use \href with a hash (even with escaping). A LaTeX forum suggested that \url can be used instead (which worked for me):

\url{http://highered.mcgrew-hill.com/classware/ala.do?blahblah=true#}

Answer 3

I had an URL with two # signs in it (a matrix server link). The second one was ignored even with escaping. What worked for me: replace the second occurrence with its urlencoding value:

\href{https://example.com/foo\#bar\%23baz}{https://example.com/foo\#bar\#baz}