How to hide or disable in-function printed message

Question

Suppose I have a function such as:

ff <- function(x) {
  cat(x, \"\\n\")
  x^2}

And run it by:

y <- ff(5)
# 5 
y
# [1         


        

Answer 1

You can use capture.output with invisible

> invisible(capture.output(y <- ff(2)))
> y
[1] 4

or sink

> sink("file")
> y <- ff(2)
> sink()
> y
[1] 4