Nick Cox
>
> -charlist-
> ==========
>
> Finally, this utility may be of use or interest:
>
> =========== begin
> program def charlist, rclass
> *! NJC 1.0.0 17 Dec 2002
> version 7
> syntax varname(string) [if] [in]
> marksample touse, novarlist
> * not 0: see [P] file formats .dta
> forval i = 1/255 {
> capture assert index(`varlist', char(`i')) ==
> 0 if `touse'
> if _rc {
> local c = char(`i')
> local charlist "`charlist'`c' "
> local numlist "`numlist'`i' "
> }
> }
> di as text "`charlist'"
> return local charlist "`charlist'"
> return local numlist "`numlist'"
> end
> ========== end
>
There's a bug in this version of -charlist-,
mirroring a longstanding misfeature (bug?)
in Stata itself. User-programmers may find
a short discussion of interest; others
may want, at most, to know that the bug is
fixed.
In accumulating characters actually met
I added them to a list by
local c = char(`i')
local charlist "`charlist'`c' "
Why didn't I go
local charlist = "`charlist'" + char(`i')
Because this fails on strings longer than
the allowed limit in string expressions.
However, if char(`i') is char(32), i.e.
a space " ",
local c = char(32)
will _not_ put a space in the local
macro -c-. If you don't believe this,
try
local c = char(32)
di "|`c'|"
This is a longstanding behaviour
of Stata, which strips leading spaces
from string expressions. I have
been told its historical rationale,
which I can't recall at present.
Whatever, a work-around is this:
if char(`i') == " " {
local c " "
}
else local c = char(`i')
local charlist "`charlist'`c' "
Note that
local c = cond(`i' == 32, " ", char(`i'))
would not work for exactly the
same reason.
I'll post a fixed version
of -charlist- to SSC.
Nick
[email protected]
*
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