non-consing count

Hi,
to count vector elements with some property, the standard idiom seems to
be length(which):
--8<---------------cut here---------------start------------->8---
x <- c(1,1,0,0,0)
count.0 <- length(which(x == 0))
--8<---------------cut here---------------end--------------->8---
however, this approach allocates and discards 2 vectors: a logical
vector of length=length(x) and an integer vector in which.
is there a cheaper alternative?
Thanks!

Sam Steingold (http://sds.podval.org/) on Ubuntu 12.04 (precise) X 11.0.11103000
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