c++ - 数组 C++ 的 Ofstream 文本编写问题

Question

好吧，我已经两次遇到问题的臭名昭著的代码项目已基本重新格式化。现在，它看起来像这样:

#include <iostream>
#include <string>
#include <fstream>

using namespace std;


struct Course
{
    string name;
    double grade;
    int block;
};

Course enter_course()
{
    Course foo;

    cout << "What is the name of the course you wish to enter?\n";
    cin >> foo.name;
    cout << "What block is " << foo.name << " ?\n";
    cin >> foo.block;
    cout << "What is your current grade as a percent?";
    cin >> foo.grade;

    return foo;
}

void display_courses(Course courseList[10], int courseCount)
{
    for (int i=0; i<courseCount; i++){
        cout << i+1 << "\t" << courseList[i].name 
            << "\t\tBlock: " << courseList[i].block
            << "\tGrade: " << courseList[i].grade << "%" << endl;
    }
}

double get_gpa(Course courseList[10], int courseCount)
{
    double gradePoints;
    double total = 0.0;
    for (int i=0; i<courseCount; i++){
        if (courseList[i].grade < 100){
            gradePoints = 4;
        } 
        if (courseList[i].grade < 90){
            gradePoints = 3;
        }
        if (courseList[i].grade < 80){
            gradePoints = 2;
        }
        if (courseList[i].grade < 70){
            gradePoints = 1;
        }
        if (courseList[i].grade < 90){
            gradePoints = 0;
        }
        total += gradePoints;
    }

    return total*1.0/courseCount;

}

void fileOutput()   
{   
    ofstream outputFile;
    outputFile.open("userGrades.txt");
    outputFile << myCourses[10] << endl;
    outputFile.close();
    cout << "Grades saved to file!" << endl;
}

void display_options()
{
    cout << "1. Exit\n";
    cout << "2. Enter a Course\n"; 
    cout << "3. Display Courses\n";
    cout << "4. Display GPA\n";
    cout << "5. Request a text file output\n";

    cout << "\n\n";
}

int main()
{
    bool exit=0;
    int option;
    int courseCount=0;
    Course myCourses[10]; //nobody should ever take more than 10 courses! 

    while (exit == 0)
    {
        cout << "GradeBook 2.0\n";
        display_options();
        cout << "Enter a command.\n";
        cin >> option;

        switch (option)
        {
            case 1: 
                exit = 1;
                break;
            case 2:
                myCourses[courseCount] = enter_course();
                courseCount++;
                break;
            case 3:
                display_courses(myCourses, courseCount);
                break;
            case 4:
                cout << get_gpa(myCourses, courseCount) << endl;
                break;
            case 5:
                fileOutput();
                break;
        }
    }

    return 0;
}

但是，在 fileOutput() 函数中，同一行代码我遇到了这些错误:

错误 C2065:“我的类(class)”:未声明的标识符IntelliSense:标识符“myCourses”未定义

我唯一能理解的是我需要在别处声明 myCourses，但我不知道如何声明。

有人认为他们可以解决这个问题吗？如果是这样，请编译代码并查看。此外，get_gpa 函数似乎无法正常工作，如果您也可以查看一下。

Answer 1

您的 Course 类没有 ostream 运算符，因此您不能在这一行中调用该运算符:

   outputFile << myCourses[10] << endl;

您可以尝试删除该行并放入:

display_courses(myCourses,courseCount)

但遗憾的是打印到 cout。因此，您确实需要重写 display_courses 以获取 ostream& 参数并输出到它，而不是 cout。