#utility functions

readinteger <- function()
{ 
  n <- readline(prompt="Enter an integer: ")
  if(!grepl("^[0-9]+$",n))
  {
    return(readinteger())
  }
  return(as.integer(n))
}

# real program start here
  
num <- round(runif(1) * 100, digits = 0)
guess <- -1

cat("Guess a number between 0 and 100.n")

while(guess != num)
{ 
  guess <- readinteger()
  if (guess == num)
  {
    cat("Congratulations,", num, "is right.n")
  }
  else if (guess < num)
  {
    cat("It's bigger!n")
  }
  else if(guess > num)
  {
    cat("It's smaller!n")
  }
}

> source("random-number-game.r")
Guess a number between 0 and 100.
Enter an integer: 50
It's smaller!
Enter an integer: 20
It's bigger!
Enter an integer: 40
It's bigger!
Enter an integer: 45
It's smaller!
Enter an integer: 43
It's bigger!
Enter an integer: 44
Congratulations, 44 is right.

The readinteger function has been explained in a previous example.

Rounding

The round function rounds the first argument to the specified number of digits.

> round(22.5,0)  # rounds to even number
[1] 22
> round(3.14,1)
[1] 3.1

Getting a random number

runif generates random numbers between 0 and 1. The first argument specifies how many numbers you want.

runif(2)

[1] 0.8379240 0.1773677

R Examples for Beginners – Guess a random number game in R

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