Why is this snippet:


rendered to this?


and not the intended:

  • I believe that url makes use of verbatim.
    – Sigur
    Apr 8, 2013 at 14:32
  • You are probably right @Sigur, but why does \Subject{} get expanded but not \lowercase?
    – SlimJim
    Apr 8, 2013 at 14:33
  • \lowercase is not an expandable command. Apr 8, 2013 at 14:34
  • @sigur: url proves a \verb-like command but does not use verbatim to do so. Apr 8, 2013 at 15:52

2 Answers 2


\lowercase (and {}) are not expandable so you need to change the order of execution:







If you need to remove space you need to use expansion only if you are not going to interfere with \url. Fortunately LaTeX has a built-in command to remove spaces via expansion:

\newcommand{\Subject}{Skeleton bones}
  \edef\tmp{\lowercase{\noexpand\url{http://www.cheatsheet.jim.pm?subject=\zap@space#1 \@empty}}}%


  • it works but I have no clue how, know I want to remove spaces from the \Subject with \StrSubstitute{#1}{ }{} but I cannot get it to compile and show properly, I tried putting inside the lcURL at different places as well as a function RemoveSpace that mimics the magic from lcURL but all in vain. The most common error is ! Argument of \reserved@a has an extra }.
    – SlimJim
    Apr 8, 2013 at 21:41
  • 1
    I don't think \StrSubstitute works via expansion so it will interfere with \url, see update. Apr 8, 2013 at 22:04

Just to see how one can use \StrSubstitute in this context:


\newcommand{\Subject}{Ske Le Ton}

  \StrSubstitute{#1}{ }{}[\tmp]%





With \begingroup and \endgroup we make sure that any definition of \tmp vanishes after usage.

enter image description here

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