Class1 a; Class2 b; if (o is Class1) { Console.WriteLine ("o is Class1"); a = (Class1)o; // do something with a } else if (o is Class2) { Console.WriteLine ("o is Class2"); b = (Class2)o; // do something with b } else { Console.WriteLine ("o is neither Class1 nor Class2."); } } public static void Main() { Class1 c1 = new Class1(); Class2 c2 = new Class2(); Test (c1); Test (c2); Test ("a string"); } } 输出 o is Class1 o is Class2 o is neither Class1 nor Class2. 7.三元操作符 三元操作符(?:)也称条件操作符。对条件表达式"b?x:y",总是先计算条件b,然后进行判断。如果b的值为true,则计算x的值,否则计算y的值。条件运算符为右联运算符,因此该形式的表达式 a ? b : c ? d : e 按如下规则计算:a ? b : (c ? d : e) 8. . 运算符 点运算符用于成员访问。name1 . name2 class Simple { public int a; &上一页 [1] [2] [3] [4] 下一页 |