area = function(r){
  return(round((pi*r^2),2))


}
diameter = function(r){
  return (2*pi)
}
circumference = function(r){
  return (round((2*pi*r),2))
}
calCircle = function(){
  radius = as.numeric(readline("Enter value for radius (cm):"))
  message("Calculate:\n(A)rea\n(C)ircumference\n(D)iameter")
  option = readline("Option:")
  calculation = switch(option,A="Area",C="Circumference",D="Diameter","Error")
  result=switch(option,A=area(radius),C=circumference(radius),D=diameter(radius),"Error")
  if(result !="Error"){
    print(paste("The",calculation,"of the circle in cm is",result))

  }else{
    print("Invalid option")
  }
}
getRadius = function(){
  radius = as.numeric(readline("Enter value for radius (cm):"))
  return(radius)
}
getOption = function(){
  message("Calculate:\n(A)rea\n(C)ircumference\n(D)iameter")
  option = readline("Option:")
  return(option)
}
printoutput(calc,res){
mainfunction = function(){
  radius=getRadius()
  option=getOption()
  calculation=switch(option,A="Area",C="Circumference",D="Diameter","Error")
  result=switch(option,A=area(radius),C=circumference(radius),D=diameter(radius),"Error")
  printoutput(calculation,result)}
mainFunction()


}