Patrick Burns wrote:
Peter Dalgaard wrote:
megh wrote:
Is there anything like "goto" loop, which exists in most computer
programs?
e.g. I am looking for this kind of stuff :
if(i < 6) goto "step-02"
Any idea?
Regards,
It doesn't exist, but it can always be replaced by if() {} else {}
constructs. (You don't usually see goto in the class of "functional
programming languages" to which R belongs. See also
http://en.wikipedia.org/wiki/Edsger_W._Dijkstra .)
R does have break, next, and return() which cover some common cases
where goto might be used with some reason.
'switch' might well be added to this list.
Hmm, no, I don't think so. The switch expression belongs with structured
programming paradigms like if, while, for. (Also, by the way, the fact
that it can be implemented as a function call in R is a nice
illustration of what lazy evaluation means).
The other ones, say "break", cover situations where goto might be used
like this
while ( cond ){
if(...) goto exit;
....
}
exit:
...
which can be implemented using plain if and while, but becomes rather
painful:
while (cond & !done){
if (....) {
done <- TRUE
} else [
.....
}
}
Similarly, "continue" jumps to a virtual label at the end of (but
inside) the loop and return() corresponds to a jump to the end of a
function.
--
O__ ---- Peter Dalgaard Øster Farimagsgade 5, Entr.B
c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907
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