数组 C++ 的 Ofstream 文本写入问题

Question

好的，我已经两次遇到问题的臭名昭著的代码项目已在很大程度上重新格式化。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，我在同一行代码中遇到了这些错误：

错误 C2065：“myCourses”：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其他地方声明 myCourses，但我不知道如何。

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

Answer 1

您的 Course 课程没有 ostream 运算符，因此您不能在此行中调用该运算符：

   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，这会打印到 cout。因此，您确实需要重新编写 display_courses 以获取 ostream& 参数并输出到它，而不是 cout。

Answer 2

在您的 fileOutput 函数中执行以下操作：

for (int i = 0; i < courseCount; i++)
 {
     outputFile << myCourses[i].name << " " << myCourses[i].grade << " " << myCourses[i].block << endl;

 }

outputFile.close();

将" " 替换为您想用来分隔文件内容的任何内容。

或者，您可以研究运算符重载并查看 ofstream 运算符的重载。