On 28.05.2018 11:07, Gábor Csárdi wrote:
> stdin() is not the same as file("stdin"), see the note in ?stdin.
In particular stdin() works in an interactive session but not when R -f
/ Rscript is used, since it does not wait for the user to input anything:
$ R -f readLines.R
R version 3.5.0 (2018-04-23) -- "Joy in Playing"
Copyright (C) 2018 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)
[...]
> create_matrix <- function() {
+ cat("Write the numbers of vertices: ")
+ user_input <- readLines(stdin(), n=1)
+ user_input <- as.numeric(user_input)
+ print(user_input)
+ }
> create_matrix()
Write the numbers of vertices: numeric(0)
>
>>>>>>> Martin Maechler
>>>>>>> on Mon, 28 May 2018 10:28:01 +0200 writes:
>> > It "works" if you additionally (the [Enter], i.e., EOL) you also
>> > "send" an EOF -- in Unix alikes via <Ctrl>-D
From my point of view this is a reasonable workaround for now.
Thanks
Ralf
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