当我打印这些学生作业时，我遇到了问题。我认为问题在于Course.cpp中的复制构造函数。 在主要课程“TestCourse.cpp”中，我用课程对象course1，course2和course3填写课程对象的课程和学生信息。 course3使用复制构造函数复制course1的属性，并在输出中显示。
问题：如果你查看course1输出，它会添加第一个新学生（“新学生1”），我在复制后添加到course3，但只在第一个course1输出中添加。如果我复制course2也会这样做。我怎么能解决这个/我做错了什么？作业已经上交，但下面的知识就不会受到影响：
标头文件
$locals['companies'] = Company::orderBy('name')->get(['id','name'])->toIndexedArray();
**包含函数**的Course.cpp
/*
* Course.h
*
*HEADER FILE
*/
#ifndef COURSE_H_
#define COURSE_H_
#include <string>
namespace std {
class Course {
public:
Course(const string& CourseName, int Capacity);
Course(const Course&);
~Course();
//declaration for copy constructor goes here
string getCourseName() const;
void addStudent(const string& Name);
void dropStudent(const string& Name);
string* getStudents() const;
int getNumberOfStudents() const;
int getCapacity();
void Clear();
//declaration for clear function goes here
private:
string CourseName;
string* Students;
int NumberOfStudents;
int Capacity;
};
} /* namespace std */
#endif /* COURSE_H_ */`
**司机班**
/*
* Course.cpp
*
* Created on: Nov 4, 2016
* Author: diez
*/
#include "Course.h"
#include <iostream>
#include <string>
#include <iterator>
namespace std {
//Course Constuctor
Course::Course(const string& CourseName, int Capacity) {
NumberOfStudents = 0;
this-> CourseName = CourseName;
this-> Capacity = Capacity;
Students = new string[Capacity];
}//end constructor
//Destructor
Course::~Course()
{
delete [] Students;
}//END Destructor
//Getter for Course Name
string Course::getCourseName() const
{
return CourseName;
}//END get
// Code to add Student to Course Object
void Course::addStudent(const string& Name)
{
//new array w/ doubly capacity
string* newArr;
newArr= new string[Capacity * 2];
if(NumberOfStudents >= Capacity)
{
Capacity *= 2;
//Loop setting new array equal to old array
for ( int i = 0; i < getNumberOfStudents(); i++)
{
newArr[i] = Students[i];
}
//Sets old array to new array's capacity and information
Students = newArr;
}//endif
//adds students to array
Students[NumberOfStudents] = Name;
NumberOfStudents++;
}//END ADD STUDENT
/*******************************
* DROP STUDENT FUNCTION
*****************************/
void Course::dropStudent(const string& Name){
/* For Loops looks through array elements*/
for(int i=0; i< getNumberOfStudents(); i++)
{
/* If element is the specified student */
if(Students[i]==Name)
{
/*Set element equal to the next */
for(int j=i; j<(getNumberOfStudents()); j++)
{
Students[j]=Students[j+1];
}
}
}
NumberOfStudents--;
}// DROP STUDENT
string* Course::getStudents() const{
return Students;
}
int Course::getNumberOfStudents() const{
return NumberOfStudents;
}
int Course::getCapacity() {
return Capacity;
}
/********************************
* CLEAR FUNCTION
************************************/
void Course::Clear(){
for (int i = 0; i < NumberOfStudents; i++){
Students[i] = " ";
}
NumberOfStudents = 0;
}//CLEAR
/******************
*COPY CONSTRUCTOR
*****************/
Course::Course(const Course& Course){
CourseName = Course.CourseName;
Capacity = Course.Capacity;
NumberOfStudents = Course.NumberOfStudents;
Students = Course.Students;
}
} /* namespace std */
编辑::这是输出
//============================================================================
// Name :
// Author :
// Date : 11/04/16
// Copyright : Your copyright notice
// Description :
/* :Program does not include double capacity function rather, doubles the capacity in the addStudent function
:Program implements the dropStudent function
:Program includes a new function named clear() that removes all of the students from the course
:Program implements the destructor and copy constructor to perform a deep copy in the class
:A third course is created that adds five students, removes one and displays the students in the course.*/
// :
//============================================================================
#include <iostream>
#include "Course.h"
using namespace std;
int main() {
//instances of Course w/ name and capacity
Course course1("Data Structures", 10);
Course course2("Database Systems", 15);
course1.addStudent("Peter Jones");
course1.addStudent("Lisa Walker");
course1.addStudent("Kevin Medara");
course1.addStudent("Joe Sansone");
course1.addStudent("Shari Bemis");
course1.addStudent("Vishnu");
course1.addStudent("Kieth Naeck");
//course 2 adding
course2.addStudent("Jacob Fraser");
course2.addStudent("Bob Walker");
course2.addStudent("Kevin Medara");
course2.addStudent("Joe Sansone");
course2.addStudent("Shari Bemis");
course2.addStudent("Melissa Johnson");
// USES COPY CONSTRUCTOR in 'Course.cpp'
Course course3(course1);
/*
* ADD 5 STUDENTS TO COURSE 3
* and force array expansion
*/
course3.addStudent("NEW STUDENT 1");
course3.addStudent("NEW STUDENT 2");
course3.addStudent("NEW STUDENT 3");
course3.addStudent("NEW STUDENT 4");
course3.addStudent("NEW STUDENT 5");
/**************************************************
* COURSE 1 CONSOLE OUTPUT
***************************************************/
/* **NOTE**
* each course output has the same properties, course3 copies the properties
* of course1
*/
cout << "Class: " << course1.getCourseName() << " | Number Of Students: "
<< course1.getNumberOfStudents() << "\nStudents In Course One "
<< " Capacity: " << course1.getCapacity() << endl; // prints !!!Hello World!!!
/*pointer string array to iterate through course Students*/
string* students = course1.getStudents();
for (int i = 0; i <= course1.getNumberOfStudents(); i++) {
cout << i << " " << students[i] << endl;
}
cout << "_____________________________________" << endl;
/*************************************************
* COURSE 2 CONSOLE OUTPUT
*************************************************/
cout << "Class: " << course2.getCourseName() << " | Number Of Students: "
<< course2.getNumberOfStudents() << "\nStudents In Course Two "
<< " Capacity: " << course2.getCapacity() << endl;
students = course2.getStudents();
for (int i = 0; i <= course2.getNumberOfStudents(); i++) {
cout << i << " " << students[i] << "\n";
}
cout << "______________________________________" << endl;
/*********************
* COURSE 3 CONSOLE OUTPUT
*deep copies console 1
*************************************/
cout << "Class: " << course3.getCourseName() << " | Number Of Students: "
<< course3.getNumberOfStudents() << "\nStudents In Course Three "
<< " Capacity: " << course3.getCapacity() << endl;
students = course3.getStudents();
for (int i = 0; i <= course3.getNumberOfStudents(); i++) {
cout << i << " " << students[i] << "\n";
}
cout << "_____________________________________" << endl;
/***********************************************************************************
* CALL DROP STUDENT FUNCTION on course1
* w/ print out
*******************************************/
course1.dropStudent("Kevin Medara");
cout << "Course One after dropping myself\n" << "Class: "
<< course1.getCourseName() << " | Number Of Students: "
<< course1.getNumberOfStudents() << "\nStudents In Course One "
<< " Capacity: " << course1.getCapacity() << endl;
students = course1.getStudents();
for (int i = 0; i < course1.getNumberOfStudents(); i++) {
cout << i << " " << students[i] << endl;
}
cout << "_____________________________________" << endl;
/**********************
* CALL CLEAR FUNCTION OF COURSE 1
* w/ print out
****************************/
course1.Clear();
cout << "Cleared Course One\n" << "Class: " << course1.getCourseName()
<< " | Number Of Students: " << course1.getNumberOfStudents()
<< "\nStudents In Course One " << " Capacity: "
<< course1.getCapacity() << endl;
students = course1.getStudents();
for (int i = 0; i <= course1.getNumberOfStudents(); i++) {
cout << i <<" " << students[i] << endl;
}
cout << "_____________________________________" << endl;
/**********************************
* DROP STUDENT FROM COURSE 3
* w/ print
************************************/
course3.dropStudent("Shari Bemis");
cout << "Course 3 After Dropping Shari Bemis\n" << "Class: "
<< course3.getCourseName() << " | Number Of Students: "
<< course3.getNumberOfStudents() << "\nStudents In Course Three "
<< " Capacity: " << course3.getCapacity() << endl;
students = course3.getStudents();
for (int i = 0; i <= course3.getNumberOfStudents(); i++) {
cout << i <<" "<< students[i] << "\n";
}
cout << "_____________________________________" << endl;
return 0;
}
答案 0 :(得分：1)
将复制构造函数更改为：
Course::Course(const Course& Course)
{
CourseName = Course.CourseName;
Capacity = Course.Capacity;
NumberOfStudents = Course.NumberOfStudents;
cout << &Students << endl;
cout<< Course.Students;
//allocate the new memory
Students = new string[Capacity];
//actually copy over the data, which was apparently the problem
for(int i = 0; i < NumberOfStudents; i ++)
{
Students[i] = Course.Students[i];
}
}