小错误- [英] Small error -

问题描述

错误1预期的类，委托，枚举，接口或结构Program.cs 20 12
错误无效"
|
\/
静态void ProcessAndDisplayNumber(DoubleOp操作，双精度值)
{
Console.WriteLine("\ nProcessAndDisplayNumber调用，值=" +值);
动作(值);
}

课程计划
{
静态void Main(string [] args)
{
DoubleOp操作=新的DoubleOp(MathOperations.MultiplyByTwo);
操作+ =新的DoubleOp(MathOperations.Squre);
ProcessAndDisplayNumber(operations，2.0);
ProcessAndDisplayNumber(operations，7.94);
ProcessAndDisplayNumber(operations，1.414);
Console.WriteLine();
}
}

Error 1 Expected class, delegate, enum, interface, or struct Program.cs 20 12
Error ''void''
|
\/
static void ProcessAndDisplayNumber(DoubleOp action, double value)
{
Console.WriteLine("\nProcessAndDisplayNumber called with value = " + value);
action(value);
}

class Program
{
static void Main(string[] args)
{
DoubleOp operations = new DoubleOp(MathOperations.MultiplyByTwo);
operations += new DoubleOp(MathOperations.Squre);
ProcessAndDisplayNumber(operations, 2.0);
ProcessAndDisplayNumber(operations, 7.94);
ProcessAndDisplayNumber(operations, 1.414);
Console.WriteLine();
}
}

推荐答案

将代码放入类struct ...，

例如

Put the code inside class, struct ...,

for example

class mySuperClassName
{
}

static void ProcessAndDisplayNumber(DoubleOp action, double value)
{
Console.WriteLine("\nProcessAndDisplayNumber called with value = " + value);
action(value);
}

必须移到您的
侧

Has to be moved in side your

class Program
{
...
}

可以将Program的类更改为静态的Program

Can change class Program to static class Program

您已经修改并破坏了Wrox出版的《 Professional C#2008》一书中的示例代码.为什么不回到原始位置查看做错了什么?

可在此处示例代码下载 [ ^ ]

为方便起见，这里是您破坏的代码.

You have modified and broken sample code from the book Professional C# 2008 published by Wrox. Why don''t you just go back to the original to see what you have done wrong?

It available here Sample code download[^]

For your convenience here is the code that you have broken.

using System;
using System.Collections.Generic;
using System.Text;

namespace Wrox.ProCSharp.Delegates
{
   class MathOperations
   {
      public static double MultiplyByTwo(double value)
      {
         return value * 2;
      }

      public static double Square(double value)
      {
         return value * value;
      }
   }


   delegate double DoubleOp(double x);

   class MainEntryPoint
   {
      static void Main()
      {
         DoubleOp[] operations =
            {
               MathOperations.MultiplyByTwo,
               MathOperations.Square
               //new DoubleOp(MathOperations.MultiplyByTwo),
               //new DoubleOp(MathOperations.Square)
            };

         for (int i = 0; i < operations.Length; i++)
         {
            Console.WriteLine("Using operations[{0}]:", i);
            ProcessAndDisplayNumber(operations[i], 2.0);
            ProcessAndDisplayNumber(operations[i], 7.94);
            ProcessAndDisplayNumber(operations[i], 1.414);
            Console.WriteLine();
         }
      }

      static void ProcessAndDisplayNumber(DoubleOp action, double value)
      {
         double result = action(value);
         Console.WriteLine(
            "Value is {0}, result of operation is {1}", value, result);
      }
   }
}

艾伦.

Alan.

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