到目前为止，我不喜欢任何答案，一点也不喜欢.数据应与代码分开；代码不应包含任何立即数(硬编码).应该是这样的:

I don''t like any of the Answers so far, not at all. Data should be separated from the code; code should not contain any immediate constants (hard-coded). It should be something like that:

//data associated with symbols:
enum Grade { F = -1, D = 60, C = 70, B = 80, A = 90, }

//...

//code, no numeric literals:
static Grade GetGrade(double age) {
    for (Grade grade = Grade.A; grade > Grade.F; grade--)
        if (age > (int)grade)
            return grade;
    return Grade.F;
} //GetGrade

然后，您的问题是什么，您可以轻松获得评分，让您的问题变得很清楚..

Then what is your problem , you can get the grade easily, make your problem clear..

<pre lang="cs">private String GetGrade(int courseAverage)<br />
        {<br />
            string letterGrade = "";<br />
            if (courseAverage >= 90)<br />
                letterGrade = "A";<br />
            else if (courseAverage > 80)<br />
                letterGrade = "B";<br />
            else if (courseAverage > 70)<br />
                letterGrade = "C";<br />
            else if (courseAverage > 60)<br />
                letterGrade = "D";<br />
            else<br />
                letterGrade = "F";<br />
            return letterGrade;<br />
        }</pre><br />

const double homeworkWeight = 0.25;
        const double quizWeight = .35;
        const double finalExamWeight = .40;

        private String CalculateGrade(string studentName, int homework1, int homework2, int quiz1, int quiz2, int finalExam)
        {
            string letterGrade = "Incomplete";

            double homeworkContribution = 0;
            double quizContribution = 0;
            double finalExamContribution = 0;

            homeworkContribution = (homework1 + homework2) / 2 * homeworkWeight;
            quizContribution = (quiz1 + quiz2) / 2 * quizWeight;
            finalExamContribution = (finalExam) * finalExamWeight;
            double courseAverage = homeworkContribution + quizContribution + finalExamContribution;

            if (courseAverage >= 90)
                letterGrade = "A";
            else if (courseAverage > 80)
                letterGrade = "B";
            else if (courseAverage > 70)
                letterGrade = "C";
            else if (courseAverage > 60)
                letterGrade = "D";
            else
                letterGrade = "F";

            return studentName + "'s" + "\nCourse Average : " + courseAverage + "\nletterGrade : " + letterGrade;

        }