(C#)一道看似簡單卻很難答得完全正確的關於多型的問題
阿新 • • 發佈：2019-01-27
/*關於virtual,overried,new在方法和屬性上以this,base形式輸出的問題 *問主程式的輸出是什麼 */ using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace ConsoleApplication2 { class Program { static void Main(string[] args) { A a1 = new B(); a1.AM1(); B b1 = (B)a1; b1.AM1(); Console.WriteLine(); A a2 = new B(); a2.AM2(); B b2 = (B)a2; b2.AM2(); } } class A { public virtual int i { get; protected set; } public A() { this.i = 9; } public virtual void AM1() { this.i = this.i + 10000; Console.WriteLine("A.this.i="+ this.i); } public virtual void AM2() { this.i = this.i + 10000; Console.WriteLine("A.this.i=" + this.i); } } class B : A { public override int i { get; protected set; } public B() : base() { this.i = 5; } public override void AM1() { Console.WriteLine("B.this.i=" + this.i); Console.WriteLine("B.base.i=" + base.i); this.i = this.i + 100; base.i = base.i + 1000; Console.WriteLine("B.this.i=" + this.i); Console.WriteLine("B.base.i=" + base.i); } public new void AM2() { Console.WriteLine("B.this.i=" + this.i); Console.WriteLine("B.base.i=" + base.i); this.i = this.i + 100; base.i = base.i + 1000; Console.WriteLine("B.this.i=" + this.i); Console.WriteLine("B.base.i=" + base.i); } } } /* output B.this.i=5 B.base.i=0 B.this.i=105 B.base.i=1000 B.this.i=105 B.base.i=1000 B.this.i=205 B.base.i=2000 A.this.i=10005 B.this.i=10005 B.base.i=0 B.this.i=10105 B.base.i=1000 */ /*關於virtual,overried,new在方法和屬性上以this,base形式輸出的問題 *問主程式的輸出是什麼 *加了些log後 */ using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace ConsoleApplication2 { class Program { static void Main(string[] args) { A a1 = new B(); a1.AM1(); B b1 = (B)a1; b1.AM1(); Console.WriteLine(); A a2 = new B(); a2.AM2(); B b2 = (B)a2; b2.AM2(); } } class A { private int tmp; public virtual int i { get { Console.WriteLine(" A.i.get=" + this.tmp); return this.tmp; } protected set { Console.WriteLine(" A.i.set=" + value); this.tmp = value; } } public A() { this.i = 9; } public virtual void AM1() { this.i = this.i + 10000; Console.WriteLine("A.this.i=" + this.i); } public virtual void AM2() { this.i = this.i + 10000; Console.WriteLine("A.this.i=" + this.i); } } class B : A { private int tmp; public override int i { get { Console.WriteLine(" B.i.get=" + this.tmp); return this.tmp; } protected set { Console.WriteLine(" B.i.set=" + value); this.tmp = value; } } public B() : base() { this.i = 5; } public override void AM1() { Console.WriteLine("B.this.i=" + this.i); Console.WriteLine("B.base.i=" + base.i); this.i = this.i + 100; base.i = base.i + 1000; Console.WriteLine("B.this.i=" + this.i); Console.WriteLine("B.base.i=" + base.i); } public new void AM2() { Console.WriteLine("B.this.i=" + this.i); Console.WriteLine("B.base.i=" + base.i); this.i = this.i + 100; base.i = base.i + 1000; Console.WriteLine("B.this.i=" + this.i); Console.WriteLine("B.base.i=" + base.i); } } } /* output B.i.set=9 B.i.set=5 B.i.get=5 B.this.i=5 A.i.get=0 B.base.i=0 B.i.get=5 B.i.set=105 A.i.get=0 A.i.set=1000 B.i.get=105 B.this.i=105 A.i.get=1000 B.base.i=1000 B.i.get=105 B.this.i=105 A.i.get=1000 B.base.i=1000 B.i.get=105 B.i.set=205 A.i.get=1000 A.i.set=2000 B.i.get=205 B.this.i=205 A.i.get=2000 B.base.i=2000 B.i.set=9 B.i.set=5 B.i.get=5 B.i.set=10005 B.i.get=10005 A.this.i=10005 B.i.get=10005 B.this.i=10005 A.i.get=0 B.base.i=0 B.i.get=10005 B.i.set=10105 A.i.get=0 A.i.set=1000 B.i.get=10105 B.this.i=10105 A.i.get=1000 B.base.i=1000 */