.NET 面试题： C# override && overloading (C# 覆写 && 重载)

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.NET 面试题, C# ,override , overloading, 覆写, 重载,.NET,ASP.NET,

 

• override (覆写/重写):

 

方法名相同，参数的个数和类型相同，内部实现不同.

The override modifier is required to extend or modify the abstract or virtual implementation of an inherited method, property, indexer, or event.

要扩展或修改继承的方法、属性、索引器或事件的抽象实现或虚实现，必须使用 override 修饰符。

 

• overloading (重载):

Overloadable Operators (C# Programming Guide)

Operator Overloading

C# Operators

方法名相同，参数的个数或类型不同.

C# allows user-defined types to overload operators by defining static member functions using the operator keyword. Not all operators can be overloaded, however, and others have restrictions, as listed in this table:

 

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override demo：

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abstract class ShapesClass {     abstract public int Area(); } class Square : ShapesClass {     int side = 0;       public Square(int n)     {         side = n;     }     // Area method is required to avoid     // a compile-time error.     public override int Area()     {         return side * side;     }       static void Main()     {         Square sq = new Square(12);         Console.WriteLine("Area of the square = {0}", sq.Area());     }       interface I     {         void M();     }     abstract class C : I     {         public abstract void M();     }   } // Output: Area of the square = 144

 

 

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C# demo

 

 

 

 

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overloading demo：

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public static Complex operator +(Complex c1, Complex c2)     {         Return new Complex(c1.real + c2.real, c1.imaginary + c2.imaginary);     }

 

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public static Complex operator +(Complex c1, Complex c2) =>         new Complex(c1.real + c2.real, c1.imaginary + c2.imaginary);       // Override ToString() to display a complex number     // in the traditional format:     public override string ToString() => $"{this.real} + {this.imaginary}";

 

 

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using System; using System.Drawing;    class TestBaseCarClass {     static void Main()     {         Console.WriteLine(Add(1, 1));     }        static int Add(int a, int b)     {         return Add(a, b, 0, 0);     }        static int Add(int a, int b, int c)     {         return Add(a, b, c, 0);     }        static int Add(int a, int b, int c, int d)     {         return a + b + c + d;     } }

 

 

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sing System; using System.Text; using System.Collections.Generic;    class Program {     static void Main()     {         myArrayList myList = new myArrayList();            myList.Add("Hello");         myList.Add("World");         myList.Add("123456");            Console.WriteLine(myList.ToString());     } }    class myArrayList : System.Collections.ArrayList {     public override string ToString()     {         StringBuilder result = new StringBuilder();         string[] theItems = (string[])base.ToArray(typeof(string));            foreach (string item in theItems)         {             result.AppendLine(item);         }         return result.ToString();     } }

 

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参考链接：

Overload and Override：

https://social.msdn.microsoft.com/Forums/zh-CN/d76c1da8-3128-48dc-ad17-c667eebd0476/overload-and-override?forum=csharpgeneral

运算符（C# 参考）：

https://msdn.microsoft.com/zh-cn/library/s53ehcz3.aspx

可重载运算符（C# 编程指南）：

https://msdn.microsoft.com/zh-cn/library/8edha89s.aspx

C# 参考

Visual Studio 2015

 

https://msdn.microsoft.com/zh-cn/library/618ayhy6.aspx

 

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