Re-prompt readline() if the input is invalid-CodePudding

Lets say I want to ask the user for an input, a number over 10. If not, print a message and re-prompt/ask again. How can this be achieved in R? I understand that this could be solved with IF or WHILE statement, but I can´t wrap my head around this.

Example

math <- function(number_1) {

  number_1 <- readline("Enter your number: ")
  if the number is below i want to reprompt readline(...)
  
  result <- number_1 / 2 
  
  return(result)
}

CodePudding user response：

Here's a way:

math <- function() {

  result <- NA

  while (is.na(result) || result < 10) {
    text <- readline("Enter your number: ")
    result <- as.numeric(text)
  }
  
  result
}

You don't need to give any input to your function; it will get the input when it prompts the user. The is.na(result) code checks for an NA: initially the result is NA, so it will run the loop at least once, and if the user enters something that isn't a number, you'll get another one.

Since readline() returns a character value, you need as.numeric to convert it to a number.