C#数组协方差
示例
string[] strings = new[] {"foo", "bar"}; object[] objects = strings; //从字符串[]隐式转换为对象[]
此转换不是类型安全的。以下代码将引发运行时异常:
string[] strings = new[] {"Foo"}; object[] objects = strings; objects[0] = new object(); //运行时异常,对象不是字符串 string str = strings[0]; //如果上述任务成功了,那将是不好的