readline {base}

R Documentation

Read a Line from the Terminal

Description

readline reads a line from the terminal (in interactive use).

Usage

readline(prompt = "")

Arguments

prompt

the string printed when prompting the user for input. Should usually end with a space " ".

Details

The prompt string will be truncated to a maximum allowed length, normally 256 chars (but can be changed in the source code).

This can only be used in an interactive session.

Value

A character vector of length one. Both leading and trailing spaces and tabs are stripped from the result.

In non-interactive use the result is as if the response was RETURN and the value is "".

See Also

readLines for reading text lines from connections, including files.

Examples

fun <- function() {
  ANSWER <- readline("Are you a satisfied R user? ")
  ## a better version would check the answer less cursorily, and
  ## perhaps re-prompt
  if (substr(ANSWER, 1, 1) == "n")
    cat("This is impossible.  YOU LIED!\n")
  else
    cat("I knew it.\n")
}
if(interactive()) fun()

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