[NTG-context] Help with \numexpr

Hans Hagen pragma at wxs.nl
Mon May 4 19:38:16 CEST 2015


On 5/4/2015 5:21 PM, Keith McKay wrote:
> Colleagues
>
> I've written some code which should extract photos from a directory and
> a add couple of lines of description to each photo.  I'm using a
> variable (\numberText) as a counter which I was hoping to use with
> \getfromcommalist[string1, string2,...][\numberText] to add one line of
> text.  However when I try to increment the variable using \numexpr
> (\numberText=\numberText+1) \relax I get the error "You can't use
> `\numexpr' in vertical mode".
>
> I'm not familiar with \numexpr and there does not seem to be much on the
> wiki on how to use it.  Any suggestions would be helpfull.
>
> Here is the code
>
> \setupexternalfigures [directory={/Path/to/the/Photos}]
>
> \defineexternalfigure[photo][maxheight=0.4\textheight]
>
> \define \numberText{1}
>
> \starttext
>
> \dostepwiserecurse{141}{146}{1}/% //\recurselevel is part of photo
> filename. See below./
>
> {
>
> \externalfigure[sam_0\recurselevel.jpg][photo] \par /% //\recurselevel
> is part of photo filename/
>
> File Name /Path/to/the/Photos/sam_0\recurselevel.jpg\par
>
> \getfromcommalist[some text,another text,even more text,much better
> text,even better text,the ultimate text][\numberText]
>
> \commalistelement\par
>
> \numexpr (\numberText=\numberText+1) \relax \par
>
> \numberText \par
>
> }
>
> \stoptext

\newcount\FooCounter

\FooCounter=\numexpr\FooCounter+1\relax

or just

\advance\FooCounter\plusone



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