讀入動態創建的指針數組結構數組

這是一個必須使用動態創建的Course數組完成的類指派。我正試圖讀取每個成員變量裏面的我的for循環，但我不知道如何去做。我用我的學生結構做了它，但是這是一個數組的差異讓我感到困惑，因爲我不知道如何繼續。讀入動態創建的指針數組結構數組

我的問題是在嘗試讀取struct成員時在readCourseArray函數中。如果有人能告訴我我該怎麼做，我會很感激。我知道使用new經營者不得與許多指針是不必要沿着理想，但它是我的教練是多麼需要分配中被打開。

#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; 
}

來源

2012-02-22 sircrisp

你應該知道的一件直接的事情是，在返回指針的函數中，你不應該返回一個局部變量。當你在函數中創建一個指針時，當函數結束時它會超出範圍，當你嘗試使用現在已故的數據時會遇到問題。當你使用'cin'讀取變量時，'coursePTR [count]'被視爲一個普通變量，所以使用'。 operator'。你會使用'coursePTR'上的箭頭。 'coursePTR [count]'已經被解除引用，因爲'coursePTR [count]'被讀爲'*（coursePTR + count）' – chris 2012-02-22 23:30:21

數組下標運算符將返回數組的元素。

coursePTR[count]相當於將指針遞增到數組的開始並取消引用結果，如：*(coursePTR + count)。你得到的是一個類型爲Course的對象（或一個對象的引用）。所以你需要使用「點」操作符，而不是「箭頭」操作符來訪問的元素：

cin >> coursePTR[count].creditHours;

你已經有了另一個錯誤：

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

這不會編譯。 endl只能用於輸出流。

來源

2012-02-22 23:37:40 jrok

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; 
}

來源

2012-02-22 23:40:41 vvnraman

讀入動態創建的指針數組結構數組

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