读入动态创建的指针数组结构数组

Question

这是一个必须使用动态创建的Course数组完成的类指派。我正试图读取每个成员变量里面的我的for循环，但我不知道如何去做。我用我的学生结构做了它，但是这是一个数组的差异让我感到困惑，因为我不知道如何继续。

我的问题是在尝试读取struct成员时在readCourseArray函数中。如果有人能告诉我我该怎么做，我会很感激。我知道使用new经营者不得与许多指针是不必要沿着理想，但它是我的教练是多么需要分配中被打开。

#include <iostream> 
#include <string> 
using namespace std; 

struct Student 
    { 
     string firstName, lastName, aNumber; 
     double GPA; 
    }; 
struct Course 
    { 
     int courseNumber, creditHours; 
     string courseName; 
     char grade; 
    }; 

Student* readStudent(); 
Course* readCourseArray(int); 
int main() 
{ 
    int courses = 0; 
    Student *studentPTR = readStudent(); 
    Course *coursePTR = readCourseArray(courses); 


    delete studentPTR; 
    delete coursePTR; 
    system ("pause"); 
    return 0; 
} 

Student* readStudent() 
{  Student* student = new Student; 
    cout<<"\nEnter students first name\n"; 
    cin>>student->firstName; 
    cout<<"\nEnter students last name\n"; 
    cin>>student->lastName; 
    cout<<"\nEnter students A-Number\n"; 
    cin>>student->aNumber; 


    return student; 
} 

Course* readCourseArray(int courses) 
{ 
    cout<<"\nHow many courses is the student taking?\n"; 
    cin>>courses; 
    const int *sizePTR = &courses; 
    Course *coursePTR = new Course[*sizePTR]; 

    for(int count = 0; count < *sizePTR; count++) //Enter course information 
    { 
     cout<<"\nEnter student "<<count<<"'s course name\n"; 
     cin>>coursePTR[count]->courseName>>endl; 
     cout<<"\nEnter student "<<count<<"'s course number\n"; 
     cin>>coursePTR[count]->courseNumber; 
     cout<<"\nEnter student "<<count<<"'s credit hours\n"; 
     cin>>coursePTR[count]->creditHours; 
     cout<<"\nEnter student "<<count<<"'s grade\n"; 
     cin>>coursePTR[count]->grade>>endl; 
    } 


    return coursePTR; 
} 

Answer 1

数组下标运算符将返回数组的元素。

coursePTR[count]相当于将指针递增到数组的开始并取消引用结果，如：*(coursePTR + count)。你得到的是一个类型为Course的对象（或一个对象的引用）。所以你需要使用“点”操作符，而不是“箭头”操作符来访问的元素：

cin >> coursePTR[count].creditHours; 

你已经有了另一个错误：

cin >> coursePTR[count].courseName >> endl; 
             ^^^^ 

这不会编译。 endl只能用于输出流。

Answer 2

Course* readCourseArray(int &courses); // Update the definition to pass "courses" by reference. 

Course* readCourseArray(int &courses) // Pass the courses by reference so that your main() has the value updated. 
{ 
    cout<<"\nHow many courses is the student taking?\n"; 
    cin>>courses; 
    /* 
     You don't need this line. 
    */ 
    // const int *sizePTR = &courses; 

    /* 
     You've allocated space for "courses" no. of "Course" objects. 
     Since this is essentially an array of "Course" object, you 
     just have to use the "." notation to access them. 
    */ 
    Course *coursePTR = new Course[courses]; 

    /* 
     "endl" cannot be used for input stream. 
    */ 
    for(int count = 0; count < courses; count++) //Enter course information 
    { 
     cout<<"\nEnter student "<<count<<"'s course name\n"; 
     cin>>coursePTR[count].courseName; 
     cout<<"\nEnter student "<<count<<"'s course number\n"; 
     cin>>coursePTR[count].courseNumber; 
     cout<<"\nEnter student "<<count<<"'s credit hours\n"; 
     cin>>coursePTR[count].creditHours; 
     cout<<"\nEnter student "<<count<<"'s grade\n"; 
     cin>>coursePTR[count].grade; 
    } 

    return coursePTR; 
}