C++|数组，switch语句?需要一些指导

C++ | An array, switch statement? Need some guidance

本文关键字：数组 switch 语句 C++      更新时间：2023-10-16

我的目标是录取（3）名学生，给他们每个人（3）个成绩，然后是每个学生的平均成绩和字母成绩。这部分效果很好。我需要的最后一部分是取这（3）个平均成绩，把它们相加，然后再取另一个平均值，即班级的平均成绩。

我该如何获得班级平均成绩？大堆切换语句？我之所以问，是因为我真的不知道。我完全不知道如何才能做到这一点。

#include <iostream>
#include <ostream>
#include "stdafx.h"
using namespace std;
// start the program
int main() {
    // LOCAL VARIABLES
    // int student1, student2, student3;     //the (3) students -- NOT EVEN SURE
    // I NEED THIS
    int all_students; // number of students
    double grade1, grade2, grade3; // the (3) grade variable declarations
    double grade_total; // holds the sum of all grades
    double grade_avg; // holds the average of the sum of grades
    cout << "Enter the number of students in the class: "; // number of students
                                                           // request
    cin >> all_students;
    all_students = 1; // initialize counter for the loop
    // need to create a loop for all three students and input for 3
    // grades/student
    while (all_students <= 3) // start the loop for the students
    {
        cout << "nnPlease enter (3) numeric grades for student "
             << all_students << ":"; // enters the 3 grades for student
        cin >> grade1 >> grade2 >>
            grade3; // the grades are stored in these 3 variables
        grade_total = grade1 + grade2 +
                      grade3; // sum is the 3 sets of graders added together
        grade_avg = grade_total / 3; // avg. is the sum divided by 3
        // displays the output for the student grades, grade average, and letter
        // grade
        cout << "Student " << all_students << " grades are n" << grade1 << "n"
             << grade2 << "n" << grade3 << "n"
             << "with an average of: " << grade_avg
             << ", which is letter grade: "; // need this line to also read the
                                             // letter grade for the average
                                             // grade
        if (grade_avg >= 90) // 90+ gets an A
            cout << "A";
        else if (grade_avg >= 80) // 80-89 gets a B
            cout << "B";
        else if (grade_avg >= 70) // 70-79 gets a C
            cout << "C";
        else if (grade_avg >= 60) // 60-69 gets a D
            cout << "D";
        else // anything less than a 60% is an F
            cout << "F";
        // increases counter!  Incrementer.
        all_students++; // Yes, I want to increment the count after the loop.
        //****************************************************************//
        //      I need to figure out how to create an array to hold       //
        //      each student average in order to calculate the overall    //
        //      class average.  Or use a switch statement?  Advice?       //
        //****************************************************************//
        //****************************************************************//
        //****************************************************************//
    }
}

您需要在while外部创建一个具有最大学生数的数组，然后在while循环内部（在循环结束时）将每个计算的平均值分配给该数组中的一个条目。

然后在while循环之外，编写一个for循环来计算数组中元素的平均值，这些元素是每个学生的平均值

最简单的方法是使用运行平均

float classAvg = 0;
const unit NUM_STUDENTS = 3;
while (all_students <= NUM_STUDENTS)       //start the loop for the students
{
  ...
  classAvg += grade_avg;
}
classAvg /= NUM_STUDENTS
cout<<"Class average is " << classAvg;

我还建议将数字等级转换为字母等级的部分转换为函数。这将使您的代码更加模块化和干净。大致如下：

void displayLetterGrade(float grade)
{
       if (grade >= 90) // 90+ gets an A
            cout << "A";
        else if (grade >= 80) // 80-89 gets a B
            cout << "B";
        else if (grade >= 70) // 70-79 gets a C
            cout << "C";
        else if (grade >= 60) // 60-69 gets a D
            cout << "D";
        else // anything less than a 60% is an F
            cout << "F";
}
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