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实现简单计算器的加减乘除运算，做到可维护、可扩展、可复用、且灵活。
可维护举例：业务人员要求加法功能只允许绝对值相加，这时修改代码的区域应只有加法，附近没有其他运算，避免不小心改到了别的运算。
可扩展举例：加个开平方根运算，添加代码的区域附近没有其他运算。
这个简单工厂用于返回运算的实例、每当有新的运算加入，工厂里的switch分支也要添加。
我要评论using system;
namespace consoleapp4
{
class program
{
public static void main(string[] args)
{
var operation = operationfactory.getoperation("+");
operation.numbera = convert.todouble(console.readline());
operation.numberb = convert.todouble(console.readline());
console.writeline(operation.getresult());
console.readline();
}
}
//运算基类
public class operation
{
private double numbera;
public double numbera
{
get { return numbera; }
set { numbera = value; }
}
private double numberb;
public double numberb
{
get { return numberb; }
set { numberb = value; }
}
public virtual double getresult()
{
double result = 0;
return result;
}
}
public class operationadd : operation
{
public override double getresult()
{
return numbera + numberb;
}
}
public class operationsub : operation
{
public override double getresult()
{
return numbera - numberb;
}
}
public class operationmul : operation
{
public override double getresult()
{
return numbera * numberb;
}
}
public class operationdiv : operation
{
public override double getresult()
{
if (numberb == 0)
{
throw new dividebyzeroexception();
}
return numbera / numberb;
}
}
// 简单工厂
public class operationfactory
{
public static operation getoperation(string operation)
{
switch (operation)
{
case "+":return new operationadd();
case "-":return new operationsub();
case "*":return new operationmul();
case "/":return new operationdiv();
default:return new operation();
}
}
}
}
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using system;
namespace consoleapp4
{
class program
{
public static void main(string[] args)
{
var cashsuper = cashfactory.createcashsuper("8折");
cashsuper.acceptcash(900d);
}
}
public abstract class cashsuper
{
public abstract double acceptcash(double money);
}
public class cashnormal : cashsuper
{
public override double acceptcash(double money)
{
return money;
}
}
public class cashrebate : cashsuper
{
private double rebate;
public cashrebate(double rebate)
{
this.rebate = rebate;
}
public override double acceptcash(double money)
{
return money * rebate;
}
}
public class cashreturn : cashsuper
{
private double moneycondition;
private double moneyreturn;
public cashreturn(double condition,double @return)
{
moneycondition = condition;
moneyreturn = @return;
}
public override double acceptcash(double money)
{
if (money >= moneycondition)
{
return money - ((money / moneycondition) * moneyreturn);
}
else
{
return money;
}
}
}
public class cashfactory
{
public static cashsuper createcashsuper(string type)
{
switch (type)
{
case "满300减50":return new cashreturn(300d, 50d);
case "8折":return new cashrebate(0.8d);
default:return new cashnormal();
}
}
}
}
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