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Re: in a loop


On 8/14/2010 6:34 AM, Bill Rowe wrote:
>
> For loops return Null. So, unless you specifically arrange for
> an output by using Print or something equivalent, no output is
> ever returned by a For loop.
>
> That is
>
> For[i = 0, i<  5, i++; i]
>
> will return nothing for exactly the same reason.
>
> One other observation, the listing created by
>
> dirnames = Names["$*Directory*"];
> For[i = 0, i<  Length[dirnames],i++; Print[dirnames[[i]]]]
>
> is more created by
>
> ColumnForm[Names["$*Directory*"]]
>
> or
>
> TableForm[Names["$*Directory*"]]
>
> which seems to me a simpler more direct approach than using
> Print in a For loop. These methods are also more efficient as
> there is no need to compute the number of items and increment an
> indexing variable.

Even simpler:

Column[Names["$*Directory*"]]

Ever since Grid and Column were introduced, I find no need for TableForm 
anymore.


-- 
Helen Read
University of Vermont


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