If the argument is not a variable in the dataset, the return code
from -confirm- will be positive, and if it is, the return code will be
zero. So,
!_rc
is non-zero if it's present and zero otherwise. So Maarten's second
example does not read quite correctly.
Nick
Maarten buis
--- Nick Cox <[email protected]> wrote:
> But even better may be to consider using -confirm-.
good point, changing my expample
sysuse auto, clear
capture confirm variable price
if !_rc {
do whatever you want to do to price
}
syuse nlsw88, clear
capture confirm variable price
if !_rc {
price is absent in this dataset
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