Input in R to calculate factorial of a number

Question

I am trying to write a program that will ask the user for an integer and calculate the integer's factorial and the program will end if the user gives a negative number. I get an

Error in while (x >= 0) { : missing value where TRUE/FALSE

needed and sometimes this

Error in x + 1 : non-numeric argument to binary operator

My code:

x <-readline(prompt="Enter an integer: ")
x <- as.integer(x)
while(x >= 0)
{
  y <- factorial(x)
  y
  x <-readline(prompt="Enter an integer: ")
  x <- as.integer(x)
}

Answer 1

Your code will work if you put everything inside a function. I improved your code and created a function myfun .

myfun <- function()
{
  z <- TRUE
  while( z )
  {
    x <- readline( prompt="Enter an integer: " )
    if ( x  < 1 ) {
      z <- FALSE
    } else {
      y <- factorial( as.numeric( x ) )
      print( y )
    }
  }
}

myfun()
# Enter an integer: 1
# [1] 1
# Enter an integer: 5
# [1] 120
# Enter an integer: -1
# >