装箱(boxing)和拆箱(unboxing)

1. 装箱(boxing)

  用于把一个值类型转换为引用类型

int i = 20;
object o = i; //隐式转换

2. 拆箱(unboxing)

  将以前装箱的值类型转换回引用类型

int i = 20;
object o = i;
int j = (int)o;