 |
[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]
Re: st: WHILE command
I believe the answer to the first question is "no":
> When does it evaluate the WHILE condition? If it becomes false
> does
> it immediately exit the WHILE loop?
That is, Stata evaluates the condition at the beginning. If true it
then executes the code in the braces. Then it evaluates the condition
again. So it does not exit in the middle of the block of code.
For example:
local i 1
while `i'==1 {
local i 0
di "this gets displayed once despite the fact"
di "that local -i- is now zero"
}
--Nick Winter
Nick Cox wrote:
Please note the -cmdname- convention flagged in the FAQ.
Eva is correct.
In addition, know that -while- knows nothing about local macros.
In this example
local i = 10
while `i' {
local --i
di `i'
}
what -while- sees is the command line after the names of any local
macros have been
replaced by their contents.
At first that is
while 10
then it is in turn
while 9
and so forth. The example also shows that the expression handled by
-while- need not be
one with two arguments and a binary operator. Any expression with
numeric result is legal.
while 1 {
...
}
would be legal too (and is sometimes useful).
Nick
[email protected]
Eva Poen
Vincent,
I believe the answers are "yes" and "yes". See the example below.
local i 0
local j 10
while `i' < `j' {
di ""
di "before updating: i `i' , j `j' "
di ""
local ++j
local i = `i' + 3
di "after updating: i `i' , j `j' "
di ""
}
di "end of loop: i `i' , j `j' "
Eva
2008/3/17, Vincent Davis <[email protected]>:
I have a few questions about the WHILE command,
1. When does it evaluate the WHILE condition? If it becomes false
does
it immediately exit the WHILE loop?
2. Can both sides of the WHILE condition be local variables that may
be updated in the WHILE statement ? WHILE 'i' < 'j' { ..... local i
= 'i' + 'j' .... local j = 'j' + 1..... }
*
* For searches and help try:
* http://www.stata.com/support/faqs/res/findit.html
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
--
--------------------------------------------------------------
Nicholas Winter 434.924.6994 t
Assistant Professor 434.924.3359 f
Department of Politics [email protected] e
University of Virginia faculty.virginia.edu/nwinter w
PO Box 400787, 100 Cabell Hall
Charlottesville, VA 22904
*
* For searches and help try:
* http://www.stata.com/support/faqs/res/findit.html
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/