c# - 无法隐式转换类型'System.Action' 到 'mathtester.Program.OperationQuestionScore'
问题描述
我做了一个 C# 控制台数学项目,用户根据他们选择的难度回答加法、减法、乘法、除法、幂或平方根问题!
这是我的完整代码:
using System;
using System.Collections.Generic;
using System.Linq;
namespace mathstester
{
class Program
{
public enum UserDifficulty
{
Easy,
Normal,
Hard
}
public enum MathOperation
{
Addition = 1,
Subtraction = 2,
Multiplication = 3,
Division = 4,
Power = 5,
SquareRoot = 6
}
public static (int operationMin, int operationMax) GetPossibleOperationsByDifficulty(UserDifficulty userDifficulty)
{
switch (userDifficulty)
{
case UserDifficulty.Easy:
return (1, 4);
case UserDifficulty.Normal:
return (1, 5);
case UserDifficulty.Hard:
return (3, 7);
default:
throw new Exception();
}
}
public class OperationQuestionScore
{
public int AdditionQuestion { get; set; }
public int AdditionScore { get; set; }
public int SubtractionQuestion { get; set; }
public int SubtractionScore { get; set; }
public int MultiplicationQuestion { get; set; }
public int MultiplicationScore { get; set; }
public int DivisionQuestion { get; set; }
public int DivisionScore { get; set; }
public int PowerQuestion { get; set; }
public int PowerScore { get; set; }
public int SquareRootQuestion { get; set; }
public int SquareRootScore { get; set; }
public static (OperationQuestionScore, OperationQuestionScore) Scores(MathOperation mathOperation)
{
Action<OperationQuestionScore> incrementOperationQuestion;
Action<OperationQuestionScore> incrementOperationScore;
switch (mathOperation)
{
case MathOperation.Addition:
incrementOperationQuestion = incrementquestion => incrementquestion.AdditionQuestion++;
incrementOperationScore = incrementscore => incrementscore.AdditionScore++;
case MathOperation.Subtraction:
incrementOperationQuestion = incrementquestion => incrementquestion.SubtractionQuestion++;
incrementOperationScore = incrementscore => incrementscore.SubtractionScore++;
break;
case MathOperation.Multiplication:
incrementOperationQuestion = incrementquestion => incrementquestion.MultiplicationQuestion++;
incrementOperationScore = incrementscore => incrementscore.MultiplicationScore++;
break;
case MathOperation.Division:
incrementOperationQuestion = incrementquestion => incrementquestion.DivisionQuestion++;
incrementOperationScore = incrementscore => incrementscore.DivisionScore++;
break;
case MathOperation.Power:
incrementOperationQuestion = incrementquestion => incrementquestion.PowerQuestion++;
incrementOperationScore = incrementscore => incrementscore.PowerScore++;
break;
case MathOperation.SquareRoot:
incrementOperationQuestion = incrementquestion => incrementquestion.SquareRootQuestion++;
incrementOperationScore = incrementscore => incrementscore.SquareRootScore++;
break;
default:
break;
}
return (incrementOperationQuestion, incrementOperationScore);
}
}
public static OperationQuestionScore Score()
{
return new OperationQuestionScore();
}
public static (string message, double correctAnswer) GetMathsEquation(MathOperation mathOperation, UserDifficulty userDifficulty)
{
int number1;
int number2;
Random randomNumber = new Random();
switch (mathOperation)
{
case MathOperation.Addition:
number1 = randomNumber.Next(1000);
number2 = randomNumber.Next(1000);
return ($"{number1} + {number2}", number1 + number2);
case MathOperation.Subtraction:
number1 = randomNumber.Next(1000);
number2 = randomNumber.Next(1000);
return ($"{number1} - {number2}", number1 - number2);
case MathOperation.Multiplication:
number1 = userDifficulty == UserDifficulty.Easy ? randomNumber.Next(13) : randomNumber.Next(1000);
number2 = userDifficulty == UserDifficulty.Easy ? randomNumber.Next(13) : randomNumber.Next(1000);
return ($"{number1} * {number2}", number1 * number2);
case MathOperation.Division:
number1 = randomNumber.Next(10000);
number2 = randomNumber.Next(1000);
return ($"{number1} / {number2}", number1 / (double)number2);
case MathOperation.Power:
number1 = randomNumber.Next(13);
number2 = randomNumber.Next(5);
return ($"{number1} ^ {number2}", Math.Pow(number1, number2));
case MathOperation.SquareRoot:
number1 = randomNumber.Next(1000);
return ($"√{number1}", Math.Sqrt(number1));
default:
throw new Exception();
}
}
public static (int, OperationQuestionScore, OperationQuestionScore) RunTest(int numberOfQuestionsLeft, UserDifficulty userDifficulty)
{
int totalScore = 0;
Random random = new Random();
var (operationMin, operationMax) = GetPossibleOperationsByDifficulty(userDifficulty);
var score = Score();
var question = Score();
var (incrementOperationQuestion, incrementOperationScore) = Scores();
while (numberOfQuestionsLeft > 0)
{
int mathRandomOperation = random.Next(operationMin, operationMax);
MathOperation mathOperation = (MathOperation)mathRandomOperation;
var (message, correctAnswer) = GetMathsEquation(mathOperation, userDifficulty);
if (mathRandomOperation == 4 || mathRandomOperation == 6)
{
Console.Write($"To the nearest integer, What is {message} =");
}
else
{
Console.Write($"What is {message} =");
}
double userAnswer = Convert.ToDouble(Console.ReadLine());
if (Math.Round(correctAnswer) == userAnswer)
{
Console.WriteLine("Well Done!");
incrementOperationQuestion(question);
incrementOperationScore(score);
totalScore++;
}
else
{
Console.WriteLine("Your answer is incorrect!");
incrementOperationQuestion(question);
}
numberOfQuestionsLeft--;
}
return (totalScore, score, question);
}
public static void Main(string[] args)
{
Dictionary<string, UserDifficulty> difficultyDictionary = new Dictionary<string, UserDifficulty>();
difficultyDictionary.Add("E", UserDifficulty.Easy);
difficultyDictionary.Add("N", UserDifficulty.Normal);
difficultyDictionary.Add("H", UserDifficulty.Hard);
string userInputDifficulty = "";
do
{
Console.WriteLine("What difficulty level would you like to do! Please type E for Easy, N for Normal and H for hard");
userInputDifficulty = Console.ReadLine().ToUpper();
} while (userInputDifficulty != "E" && userInputDifficulty != "N" && userInputDifficulty != "H");
UserDifficulty userDifficulty = difficultyDictionary[userInputDifficulty];
int numberOfQuestions = 0;
do
{
Console.WriteLine("How many questions would you like to answer? Please type a number divisible by 10!");
int.TryParse(Console.ReadLine(), out numberOfQuestions);
} while (numberOfQuestions % 10 != 0);
var (totalScore, score, question) = RunTest(numberOfQuestions, userDifficulty);
Console.WriteLine($"Total score: {totalScore} of {numberOfQuestions}");
if (userDifficulty == UserDifficulty.Easy)
{
Console.WriteLine($"Addition score: {score.AdditionScore} of {question.AdditionQuestion}");
Console.WriteLine($"Subtraction score: {score.SubtractionScore} of {question.SubtractionQuestion}");
Console.WriteLine($"Multiplication score: {score.MultiplicationScore} of {question.MultiplicationQuestion}");
}
else if (userDifficulty == UserDifficulty.Normal)
{
Console.WriteLine($"Addition score: {score.AdditionScore} of {question.AdditionQuestion}");
Console.WriteLine($"Subtraction score: {score.SubtractionScore} of {question.SubtractionQuestion}");
Console.WriteLine($"Multiplication score: {score.MultiplicationScore} of {question.MultiplicationQuestion}");
Console.WriteLine($"Division score: {score.DivisionScore} of {question.DivisionQuestion}");
}
else if (userDifficulty == UserDifficulty.Hard)
{
Console.WriteLine($"Multipication score: {score.MultiplicationScore} of {question.MultiplicationQuestion}");
Console.WriteLine($"Division score: {score.DivisionScore} of {question.DivisionQuestion}");
Console.WriteLine($"Power score: {score.PowerScore} of {question.PowerQuestion}");
Console.WriteLine($"Squareroot score: {score.SquareRootScore} of {question.SquareRootQuestion}");
}
}
}
}
这是我的问题所在:
public static (OperationQuestionScore, OperationQuestionScore) Scores(MathOperation mathOperation)
{
Action<OperationQuestionScore> incrementOperationQuestion;
Action<OperationQuestionScore> incrementOperationScore;
switch (mathOperation)
{
case MathOperation.Addition:
incrementOperationQuestion = incrementquestion => incrementquestion.AdditionQuestion++;
incrementOperationScore = incrementscore => incrementscore.AdditionScore++;
case MathOperation.Subtraction:
incrementOperationQuestion = incrementquestion => incrementquestion.SubtractionQuestion++;
incrementOperationScore = incrementscore => incrementscore.SubtractionScore++;
break;
case MathOperation.Multiplication:
incrementOperationQuestion = incrementquestion => incrementquestion.MultiplicationQuestion++;
incrementOperationScore = incrementscore => incrementscore.MultiplicationScore++;
break;
case MathOperation.Division:
incrementOperationQuestion = incrementquestion => incrementquestion.DivisionQuestion++;
incrementOperationScore = incrementscore => incrementscore.DivisionScore++;
break;
case MathOperation.Power:
incrementOperationQuestion = incrementquestion => incrementquestion.PowerQuestion++;
incrementOperationScore = incrementscore => incrementscore.PowerScore++;
break;
case MathOperation.SquareRoot:
incrementOperationQuestion = incrementquestion => incrementquestion.SquareRootQuestion++;
incrementOperationScore = incrementscore => incrementscore.SquareRootScore++;
break;
default:
break;
}
return (incrementOperationQuestion, incrementOperationScore);
}
在我的函数“分数”中,我的return (incrementOperationQuestion, incrementOperationScore);
.
错误说
1. Cannot implicitly convert type 'System.Action<mathstester.Program.OperationQuestionScore>'
to 'mathstester.Program.OperationQuestionScore'
2. Use of unassigned local variable 'incerementOperationScore'
我该如何解决?
解决方案
无法将类型“System.Action”隐式转换为“mathtester.Program.OperationQuestionScore”
发生此错误是因为方法Scores
被声明为返回一个类型的元组,(OperationQuestionScore, OperationQuestionScore)
但它实际上返回一个类型的元组(Action<OperationQuestionScore>, Action<OperationQuestionScore>)
。要解决此问题,您应该更改方法的返回类型Scores
:
public static (Action<OperationQuestionScore>, Action<OperationQuestionScore>) Scores(MathOperation mathOperation)
使用未分配的局部变量“incerementOperationScore”
此类错误表明使用了未分配给值的变量。在您的情况下,编译器告诉您有可能使用 unassigned variable incerementOperationScore
。如果参数mathOperation
与任何 switch case 都不匹配,并且空default
case 没有为 赋值,则可能会发生这种情况incerementOperationScore
。目前所有可能的mathOperation
值都由 switch 语句处理,这意味着default
分支永远不会执行。但是将来您可能会添加一个新的数学运算而忘记将其添加到此 switch 语句中。为了防止此类错误,编译器会强制我们处理所有可能的大小写值(即使我们将来会添加它们)。
要解决此问题,您应该在以下情况下抛出异常default
:
default:
throw new System.ComponentModel.InvalidEnumArgumentException("mathOperation", (int) mathOperation, typeof(MathOperation));
或处理案例中的MathOperation
值之一default
:
default: // For example, use default branch instead of MathOperation.SquareRoot branch.
incrementOperationQuestion = incrementquestion => incrementquestion.SquareRootQuestion++;
incrementOperationScore = incrementscore => incrementscore.SquareRootScore++;
break;
我个人更喜欢抛出异常。当您忘记为新添加的枚举值添加新的案例分支时,它有助于处理情况。
该方法还有另一个错误Scores
。break
第一个 case 分支中缺少关键字。
这是Scores
具有固定错误的完整方法:
public static (Action<OperationQuestionScore>, Action<OperationQuestionScore>) Scores(MathOperation mathOperation)
{
Action<OperationQuestionScore> incrementOperationQuestion;
Action<OperationQuestionScore> incrementOperationScore;
switch (mathOperation)
{
case MathOperation.Addition:
incrementOperationQuestion = incrementquestion => incrementquestion.AdditionQuestion++;
incrementOperationScore = incrementscore => incrementscore.AdditionScore++;
break;
case MathOperation.Subtraction:
incrementOperationQuestion = incrementquestion => incrementquestion.SubtractionQuestion++;
incrementOperationScore = incrementscore => incrementscore.SubtractionScore++;
break;
case MathOperation.Multiplication:
incrementOperationQuestion = incrementquestion => incrementquestion.MultiplicationQuestion++;
incrementOperationScore = incrementscore => incrementscore.MultiplicationScore++;
break;
case MathOperation.Division:
incrementOperationQuestion = incrementquestion => incrementquestion.DivisionQuestion++;
incrementOperationScore = incrementscore => incrementscore.DivisionScore++;
break;
case MathOperation.Power:
incrementOperationQuestion = incrementquestion => incrementquestion.PowerQuestion++;
incrementOperationScore = incrementscore => incrementscore.PowerScore++;
break;
case MathOperation.SquareRoot:
incrementOperationQuestion = incrementquestion => incrementquestion.SquareRootQuestion++;
incrementOperationScore = incrementscore => incrementscore.SquareRootScore++;
break;
default:
throw new InvalidEnumArgumentException("mathOperation", (int) mathOperation, typeof(MathOperation));
}
return (incrementOperationQuestion, incrementOperationScore);
}
@crazydanyal1414 在评论中问:
但是如何将“Scores”函数定义为“RunTest”?
需要对该方法进行微小的更改RunTest
。这里是改方法RunTest
。我在评论中描述了所做的更改:
public static (int, OperationQuestionScore, OperationQuestionScore) RunTest(int numberOfQuestionsLeft, UserDifficulty userDifficulty)
{
int totalScore = 0;
Random random = new Random();
var (operationMin, operationMax) = GetPossibleOperationsByDifficulty(userDifficulty);
var score = Score();
var question = Score();
// Move this line into the while loop.
//var (incrementOperationQuestion, incrementOperationScore) = Scores();
while (numberOfQuestionsLeft > 0)
{
int mathRandomOperation = random.Next(operationMin, operationMax);
MathOperation mathOperation = (MathOperation)mathRandomOperation;
var (message, correctAnswer) = GetMathsEquation(mathOperation, userDifficulty);
if (mathRandomOperation == 4 || mathRandomOperation == 6)
{
Console.Write($"To the nearest integer, What is {message} =");
}
else
{
Console.Write($"What is {message} =");
}
// Here is moved line.
// Method Scores must be invoked using static method invocation
// syntax, and a parameter mathOperation must be passed into it.
var (incrementOperationQuestion, incrementOperationScore) = OperationQuestionScore.Scores(mathOperation);
double userAnswer = Convert.ToDouble(Console.ReadLine());
if (Math.Round(correctAnswer) == userAnswer)
{
Console.WriteLine("Well Done!");
incrementOperationQuestion(question);
incrementOperationScore(score);
totalScore++;
}
else
{
Console.WriteLine("Your answer is incorrect!");
incrementOperationQuestion(question);
}
numberOfQuestionsLeft--;
}
return (totalScore, score, question);
}
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