Transform every integer to 1 or 0

Hello,

I have a dataframe with positive integers and
for every value>  0
I would like to have 1 and the rest should be zero.

For instance

1 0 1
0 1 1

with df as reference.

df

     V1 V2 V3
yes 23  0  5
no   0  5  7

dput (df)

structure(list(V1 = c(23, 0), V2 = c(0, 5), V3 = c(5, 7)), .Names = c("V1",
"V2", "V3"), row.names = c("yes", "no"), class = "data.frame")

Is there a special function?