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Re: in a loop

• To: mathgroup at smc.vnet.net
• Subject: [mg111859] Re: in a loop
• From: Helen Read <hpr at together.net>
• Date: Sun, 15 Aug 2010 07:39:56 -0400 (EDT)
• References: <i45rgj$g4u$1@smc.vnet.net>
• Reply-to: HPR <read at math.uvm.edu>

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