Replace all values in a row with 0 if one of the variables has missing data

Question

As the title states I'm attempting to replace all values in a given row with 0 if any variable has NA and output this using write.table. For example:

x  y  z
2  3  5
4  NA 1
3  2  1

to

x  y  z
2  3  5
0  0  0
3  2  1

At the moment my code looks like the following

myvars <- c("x", "y", "z")
newdata <- mydata[myvars]
write.table(newdata, "data.txt", col.names=FALSE, row.names=FALSE)

Answer 1

complete.cases seems appropriate here:

dat[!complete.cases(dat),] <- 0
dat
#  x y z
#1 2 3 5
#2 0 0 0
#3 3 2 1

Answer 2

While the answer by @thelatemail is really cool,

It won't hurt to learn one more trick.

Here is my solution:

dat[rowSums(is.na(dat))>0,]<- 0
dat
#  v1 v2 v3
#1 2  3  5
#2 0  0  0
#3 3  2  1