指针变量声明：
例：
int* p1, p2, p3;
public static unsafe void swap(int a,int b)
{
int temp;
temp = a;
a = b;
b = a;
}
public static unsafe void swapP(int* pa,int* pb)
{
int temp = *pa;
*pa = *pb;
*pb = temp;
}
private static unsafe void Main(string[] args)
{
int a = 10, b = 20;
Console.WriteLine("a:" + a + ",b:" + b);
swap(a, b);
Console.WriteLine("after swap:a:" + a + ",b:" + b);
int* pa = &a, pb = &b;
swapP(pa, pb);
Console.WriteLine("after swapP:a:" + a + ",b:" + b);
Console.ReadKey();
}
a:10,b:20
after swap:a:10,b:20
after swapP:a:20,b:10