myRoute.direction = (orientation)myDirection;什么意思

题目

myRoute.direction = (orientation)myDirection;什么意思
enum orientation :byte
{
north = 1,
south = 2,
east = 3,
west = 4
}
struct route
{
public orientation direction;
public double distance;
}
class Program
{
static void Main(string[] args)
{
route myRoute;
int myDirection = -1;
double myDistance;
Console.WriteLine("1) North 2) South 3) East 4) West");
do
{
Console.WriteLine("Select a direction:");
myDirection = Convert.ToInt32(Console.ReadLine());
}
while ((myDirection < 1) || (myDirection > 4));
Console.WriteLine("Input a distance:");
myDistance = Convert.ToDouble(Console.ReadLine());
myRoute.direction = (orientation)myDirection;
myRoute.distance = myDistance;
Console.WriteLine("myRoute specifies a direction of {0} and a " +
"distance of {1}",myRoute.direction,myRoute.distance);
Console.ReadKey();
}

答案

强制类型转换
把myDirection转换成orientation类型