Re: st: local and loops

[Matthew White <mwhite@poverty-action.org>]

Hi Nick,

Thanks for your reply.

There were supposed to be exactly two spaces between 1 and 2, and the
second string specified to -strpos()- was supposed to be two
consecutive spaces.

Outside of a loop, the internal spaces in `foo' are actually preserved
on my computer, even without the double quotes:

. local foo a                  b                  c

. display strpos("`foo'", "  ")
2

. display `:length local foo'
39

If the spaces were trimmed, the length of `foo' would be 5.

However, when I put this in a loop, I get different results:

. forvalues i = 1/5 {
  2. local foo a                  b                  c
  3. }

. display strpos("`foo'", "  ")
0

. display `:length local foo'
5

When you define `foo' outside of a loop, do you get a length of 5 or 39?

Inside and outside of a loop, leading and trailing spaces are trimmed
unless double quotes are used, but as far as I can tell, internal
spaces are typically left untrimmed.

Thank you,
Matt

On Tue, Aug 20, 2013 at 3:05 PM, Nick Cox <njcoxstata@gmail.com> wrote:
> How many spaces are there between "1" and "2"?
>
> Without " " as delimiters, Stata trims internal spaces to single
> spaces in local macro definition. The " " insist on taking things
> quite literally.
>
> Try
>
> local foo a                  b                  c
>
> and see what happens.
>
> So, -strpos()- can't find a double space as there isn't one.
>
> I don't think looping is germane here.
>
> Nick
> njcoxstata@gmail.com
>
>
> On 20 August 2013 19:52, Matthew White <mwhite@poverty-action.org> wrote:
>> Hi all,
>>
>> Using Stata 13 for Windows 7, I'm trying to figure out an interaction
>> between -local- and loops. Normally when I define a local, multiple,
>> consecutive internal spaces are preserved. For example:
>>
>> . local x 1  2
>>
>> . display strpos("`x'", "  ")
>> 2
>>
>> Yet when I use the same definition in a loop, the internal spaces are trimmed:
>>
>> . forvalues i = 1/5 {
>>   2. local x 1  2
>>   3. }
>>
>> . display strpos("`x'", "  ")
>> 0
>>
>> Have others experienced this before? It's probably rare that this
>> would bite, but I'm running into such a situation now. Enclosing the
>> contents of the local by double quotes solves the problem:
>>
>> . forvalues i = 1/5 {
>>   2. local x "1  2"
>>   3. }
>>
>> . display strpos("`x'", "  ")
>> 2
>>
>> I'm just so used to dropping these quotes when I don't need them!
>>
>> Thank you,
>> Matt
>>
>> --
>> Matthew White
>> Senior Project Associate
>> Innovations for Poverty Action
>> 101 Whitney Avenue, New Haven, CT 06510 USA
>> www.poverty-action.org
>> *
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-- 
Matthew White
Senior Project Associate
Innovations for Poverty Action
101 Whitney Avenue, New Haven, CT 06510 USA
www.poverty-action.org
*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/faqs/resources/statalist-faq/
*   http://www.ats.ucla.edu/stat/stata/