C++大学教程（第九版）5.15修改GradeBook

题目

代码

运行命令（在控制台输入）

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题目

（修改GradeBook）修改图5.9~图5.11所示的 GradeBook 程序，使它计算一组成绩的平均成绩。
成绩A为4分，成绩B为3分，依次类推。
A:4
B:3
C:2
D:1
E:0
F:-1

代码

注意有注释的位置，基本都是有修改的地方。

//5_15.h// GradeBook.h#include <string>class GradeBook
{
public:GradeBook(std::string);void setCourseName(std::string);std::string getCourseName() const;void setCourseTeacher(std::string);std::string getCourseTeacher() const;void displayMessage() const;void inputGrades();void displayGradeReport() const;private:std::string courseName;unsigned int aCount;unsigned int bCount;unsigned int cCount;unsigned int dCount;unsigned int eCount;unsigned int fCount;double gradeSum;//增加了存储分数和的变量
};

//5_15.cpp#include <iostream>
#include "5_15.h"
#include <iomanip>
using namespace std;GradeBook::GradeBook(string name) : aCount(0), bCount(0), cCount(0), dCount(0), eCount(0), fCount(0)
{setCourseName(name);
}void GradeBook::setCourseName(string name)
{if (name.size() <= 25)courseName = name;else{courseName = name.substr(0, 25);cerr << "name\"" << name << "\"exceeds maximum length(25).\n"<< "Limiting courseName to first 25 characters.\n"<< endl;}
}string GradeBook::getCourseName() const
{return courseName;
}void GradeBook::displayMessage() const
{cout << "Welcome to the grade book for " << getCourseName() << endl;
}void GradeBook::inputGrades() // 有修改
{int grade;gradeSum = 0.0; // 初始化cout << "Enter the letter grades:" << endl<< "Enter the EOF character to end input." << endl;while ((grade = cin.get()) != EOF){switch (grade){case 'A':case 'a':aCount++;gradeSum += 4; // 添加每个字母对应的分数break;case 'B':case 'b':bCount++;gradeSum += 3;break;case 'C':case 'c':cCount++;gradeSum += 2;break;case 'D':case 'd':dCount++;gradeSum += 1;break;case 'E':case 'e':eCount++;gradeSum += 0;break;case 'F':case 'f':fCount++;gradeSum += (-1);break;case '\n':case '\t':case ' ':break;default:cout << "Incorrect letter grade entered."<< "\nPlease enter a new grade." << endl;break;}}
}void GradeBook::displayGradeReport() const//有修改
{int count;cout << "\n\nNumber of students who received each letter grade:"<< "\nA:" << aCount << "\nB:" << bCount << "\nC:" << cCount<< "\nD:" << dCount << "\nE:" << eCount << "\nF:" << fCount << endl;count = aCount + bCount + cCount + dCount + eCount + fCount;                      // 求一共有多少个字母cout << "这一组成绩的平均数:" << gradeSum / (static_cast<double>(count)) << endl; // 计算平均数;
}

//5_15main.cpp#include <iostream>
#include "5_15.h"
using namespace std;int main()
{GradeBook myGradeBook("zhang san");myGradeBook.displayMessage();myGradeBook.inputGrades();myGradeBook.displayGradeReport();return 0;
}