プログラミング学習の記録 341 "初めてのC# 第2版"の第12章(演算子のオーバーロード)

開発環境

• Microsoft Windows 7 Home Premium (OS)
• Microsoft Visual C# 2010 Express Edition (IDE)
• 言語: C#

『初めてのC# 第2版』(Jesse Liberty+Brian MacDonald著、日向俊二訳、オライリー・ジャパン、2006年、ISBN978-487311-294-7)の第12章(演算子のオーバーロード)の12.6(練習問題)を解いてみる。

練習 12-1

using System; class Invoice { private string vendor; private double amount; public Invoice(string vendor, double amount) { this.vendor = vendor; this.amount = amount; } public string Vendor { get { return vendor; } set { vendor = value; } } public double Amount { get { return amount; } set { amount = value; } } public static Invoice operator +(Invoice lhs, Invoice rhs) { if (lhs.vendor == rhs.vendor) { return new Invoice(lhs.vendor, lhs.amount + rhs.amount); } else { return new Invoice("", 0); } } } class Tester { public void Run() { Invoice invoice = new Invoice("Invoice", 1.2); Invoice invoice1 = new Invoice("Invoice", 2.3); Invoice invoice2 = new Invoice("Invoice1", 1.2); Invoice invoice01=invoice+invoice1; Invoice invoice12=invoice1+invoice2; Invoice invoice20=invoice2+invoice; Console.WriteLine("invoice \tVendor: {0} Amount: {1}", invoice.Vendor, invoice.Amount); Console.WriteLine("invoice1\tVendor: {0} Amount: {1}", invoice1.Vendor, invoice1.Amount); Console.WriteLine("invoice2\tVendor: {0} Amount: {1}", invoice2.Vendor, invoice2.Amount); Console.WriteLine("\ninvoice+invoice1\tVendor: {0} Amount: {1}", invoice01.Vendor, invoice01.Amount); Console.WriteLine("invoice1+invoice2\tVendor: {0} Amount: {1}", invoice12.Vendor, invoice12.Amount); Console.WriteLine("invoice2+invoice0\tVendor: {0} Amount: {1}", invoice20.Vendor, invoice20.Amount); } static void Main() { Tester t = new Tester(); t.Run(); } }

出力結果

invoice Vendor: Invoice Amount: 1.2 invoice1 Vendor: Invoice Amount: 2.3 invoice2 Vendor: Invoice1 Amount: 1.2 invoice+invoice1 Vendor: Invoice Amount: 3.5 invoice1+invoice2 Vendor: Amount: 0 invoice2+invoice0 Vendor: Amount: 0 続行するには何かキーを押してください . . .

 

練習 12-2

using System; class Invoice { private string vendor; private double amount; public Invoice(string vendor, double amount) { this.vendor = vendor; this.amount = amount; } public string Vendor { get { return vendor; } set { vendor = value; } } public double Amount { get { return amount; } set { amount = value; } } public static bool operator ==(Invoice lhs, Invoice rhs) { if ((lhs.vendor == rhs.vendor) && (lhs.amount == rhs.amount)) { return true; } else { return false; } } public static bool operator !=(Invoice lhs, Invoice rhs) { bool equality = (lhs == rhs); return !(equality); } public override bool Equals(object obj) { if (!(obj is Invoice)) { return false; } return this == (Invoice)obj; } public override int GetHashCode() { return base.GetHashCode(); } } class Tester { public void Run() { Invoice invoice = new Invoice("Invoice", 1.2); Invoice invoice1 = new Invoice("Invoice", 1.2); Invoice invoice2 = new Invoice("Invoice", 2.3); Invoice invoice3 = new Invoice("Invoice1", 1.2); Console.WriteLine("invoice \t Vendor: {0} Amount: {1}", invoice.Vendor, invoice.Amount); Console.WriteLine("invoice1\t Vendor: {0} Amount: {1}", invoice1.Vendor, invoice1.Amount); Console.WriteLine("invoice2\t Vendor: {0} Amount: {1}", invoice2.Vendor, invoice2.Amount); Console.WriteLine("invoice3\t Vendor: {0} Amount: {1}", invoice3.Vendor, invoice3.Amount); Console.WriteLine( "invoice=invoice1 : {0}", (invoice == invoice1)); Console.WriteLine( "invoice=invoice2 : {0}", (invoice == invoice2)); Console.WriteLine( "invoice=invoice3 : {0}", (invoice == invoice3)); } static void Main() { Tester t = new Tester(); t.Run(); } }

出力結果

invoice Vendor: Invoice Amount: 1.2 invoice1 Vendor: Invoice Amount: 1.2 invoice2 Vendor: Invoice Amount: 2.3 invoice3 Vendor: Invoice1 Amount: 1.2 invoice=invoice1 : True invoice=invoice2 : False invoice=invoice3 : False 続行するには何かキーを押してください . . .