Simplify example 6

[grahamison]

The example odd_or_even function in example 6 could be improved.

Suggestions:

• Put the checks at the top
• Put the type check before the length check
• Simplify the non-integer check to x %% 1 != 0
• Consider returning odd or even rather than printing, to reflect more typical usage, and it might make the distinction between the checks and the function behaviour visually clearer.

[grahamison]

A suggested version:

# This function lets you know whether a number is odd or even
odd_or_even <- function(x) {
  
  if (!is.numeric(x)) {
    stop("x must be a number")
  }
  
  if (length(x) > 1) {
    stop("x must have length 1")
  } 
  
  if ((x %% 1) != 0) {
    stop("x must be an integer")
  }
  
  if ((x %% 2) == 0) {
    "even"
  } else {
    "odd"
  }
}