返回零的最小值[重复]

Question

我有一个程序可以找到最低和最高等级。最大值函数有效，但最小值函数返回 0。我不确定我做错了什么，我的代码中没有错误。谢谢！

使用系统； 使用 System.Collections.Generic;

命名空间等级转换器 { 课堂节目 { 静态无效主要（字符串 [] 参数） { bool doAgain = true; //float totalScore = 0 , averageScore; 字符串更多转换； int numberOfGrades;

        //Ask the user to enter their first and last name
        string userName = getName();

        //Print a welcome message: "Hello [first name] [last name] Welcome to the Grade Converter!"
        Console.WriteLine($"\nHello {userName}! Welcome to the Grade Converter!");

        while(doAgain){
            List<float> scores = new List<float>();

            //Prompt the user to enter the number of grades they need to convert "Enter the number of grades you need to convert: "
            numberOfGrades = getNumberOfGrades();

            //Prompt the user to enter the grades. The grades should be stored in a list and you should use the appropriate data type for the grades. 
            scores = populateGradesList(scores, numberOfGrades);
            
            //Print Grade Report
            printGradeReport(scores);
            printGradeStatistics(scores, numberOfGrades);
            float aveScore = getAverageGrade(scores);
            float maximumGrade = getMaximumGrade(scores);
            float minimumGrade = getMinimumGrade(scores);
            //averageScore = totalScore / numberOfGrades; 
            

            Console.WriteLine("Would you like to convert more grades (y/n)?");
            moreConversions = Console.ReadLine();

            //reset total score
            //totalScore = 0;

            if (moreConversions != "y" && moreConversions != "Y"){
                doAgain = false;
            }
        }
    }

    static float getMinimumGrade(List<float> listOfNumberGrades){
        float min = 0;;

        foreach(float grade in listOfNumberGrades){
            if( grade < min){
                min = grade;
            }
        }
        return min;
    }

    static float getMaximumGrade(List<float> listOfNumGrades){
        float max = 0;

        foreach(float grade in listOfNumGrades){
            if( grade > max){
                max = grade;
            }
            
        }
            return max;
    }

    static float getAverageGrade(List<float> listOfGrades){
        float total = 0;
        float average = 0;
        foreach(float grade in listOfGrades){
            total += grade;             
        }
        average = total / listOfGrades.Count;
        return average;
        }

    static void printGradeStatistics(List<float> listOfGrades, int numberOfGrades){
        float averageScore = getAverageGrade(listOfGrades);
        float maximumGrade = getMaximumGrade(listOfGrades);
        float minimumGrade = getMinimumGrade(listOfGrades);
        Console.WriteLine("\nGrade Statistics\n-------------------------\n");
        Console.WriteLine($"Number of grades: {numberOfGrades}");
        Console.WriteLine($"Average Grade: {averageScore} which is a {getLetterGrade(averageScore)}");
        Console.WriteLine($"Maximum Grade: {maximumGrade}");
        Console.WriteLine($"Minimum Grade: {minimumGrade}");
    }

    static void printGradeReport(List<float> scoresList){
        string letterGrade;

        Console.WriteLine();
        foreach(float testScore in scoresList){
                //Convert the number grades to letter grades (A = 90-100, B = 80-89, C = 70-79, D = 60 - 69, F lower than 60)
            letterGrade = getLetterGrade(testScore);

                //Print all the numerical grades and their corresponding letter grades to the console 
            Console.WriteLine($"A score of {testScore} is a {letterGrade} grade");  
            }
            return;

    }

    static List<float> populateGradesList(List<float> listOfScores, int numGrades){
        float score;
        for(int counter = 0; counter < numGrades; counter ++){
                score = getScores();
                listOfScores.Add(score);
            }
            return listOfScores;

    }

    static int getNumberOfGrades(){
        Console.WriteLine("\nEnter the number of grades you need to convert:");
        int numberOfGrades = int.Parse(Console.ReadLine());
        return numberOfGrades;
    }

    static string getName(){
        Console.WriteLine("Please enter your first name and last name");
        string userName = Console.ReadLine();
        return userName;
    }

    static float getScores(){
        float grade;
        while(true){
            Console.WriteLine("\nEnter the score to be converted: ");
            try{
                grade = float.Parse(Console.ReadLine());
                break;  
            }catch(FormatException){
                Console.WriteLine("Error: Only numbers allowed");
            }
        }  
        return grade;
    }

    static string getLetterGrade(float score){
        //(A = 90-100, B = 80-89, C = 70-79, D = 60 - 69, F lower than 60).
        if (score >= 90){
            return "A";
        }else if(score >= 80){
            return "B";
        }else if (score >= 70){
            return "C";
        }else if(score >= 60){
            return "D";
        }else{
            return "F";
        }
    }

}

}

Answer 1

您可以将起始值设置为列表中的第一个值。像这样的：

static float getMinimumGrade(List<float> listOfNumberGrades){
    float min = listOfNumberGrades.First();

    foreach(float grade in listOfNumberGrades){
        if( grade < min){
            min = grade;
        }
    }
    return min;
}

但请注意，如果列表中有 0 个项目，这将不起作用，而且它首先访问列表中的第一个项目。

更简单的方法是使用IEnumerable.Min:

static float getMinimumGrade(List<float> listOfNumberGrades){
    return listOfNumberGrades.Min();
}