我正在尝试在List类中创建一个动态数组，该数组将从大小为2开始，当您使用Insert方法插入值时，它将检查是否有足够的空间，否则它将调整大小大小为+ 2的数组...问题是它正在崩溃VS正在抱怨堆的损坏。另外我认为我的拷贝构造函数没有被调用，因为cout没有显示：
list.h文件：
class List
{
public:
// DEFAULT Constructor
List();
// Deconstructor to free memory allocated
~List();// Prevent memory leaks
// COPY Constructor for pointers
List(const List& value);// copy constructor
//Modification methods
void Insert(const int);
// User ACCESS methods
void display(void) const;
private:
int size;// MAX size of the array
int count;// current number of elements in the dynamic array
protected:
int *intptr;// Our int pointer
};
list.cpp实现文件：
#include "list.h" // Include our Class defintion
#include <iostream>
using namespace std;
// CONSTRUCTOR
List::List() {
size = 2; // initial size of array
count = 0;
intptr = new int[size]; // Start off 2 integers sized array
}
// DECONSTRUCTOR
List::~List() {
delete[] intptr; // free allocated memory
}
// Copy constructor
List::List(const List& value) {
size = value.size;
cout << "Copy con size : " << size << endl;
count = value.count;
cout << "Compy count : " << count << endl;
if (count < size) {
intptr = new int[size]; // Allocate new data
} else {
intptr = new int[size + 2]; // Allocate new data
}
for (int index = 0; index < count; index++) {
intptr[index] = value.intptr[index];
}
size = size + 2;
delete[] intptr;
intptr = value.intptr;
}
void List::Insert(const int value) {
// do we have room?
if (count < size) {
intptr[count] = value;
} else { // if not we need to add more elements to array
intptr[count] = value; // DEEP copy invoked with copy constructor
}
cout << "SIZE: " << size << endl;
cout << "COUNT" << count << endl;
count++; // Increase items added in array
}
void List::display() const {
for (int i = 0; i < count; i++)
cout << intptr[i] << endl;
}
main.cpp测试员
#include <iostream>
#include "list.h"
int main()
{
List mylist;
mylist.Insert(5);
mylist.Insert(6);
mylist.Insert(2);
mylist.Insert(8);
mylist.Insert(4);
mylist.Insert(5);
mylist.Insert(9);
mylist.Insert(8);
mylist.Insert(5);
mylist.Insert(9);
mylist.Insert(8);
mylist.Insert(5);
mylist.Insert(9);
mylist.Insert(8);
mylist.Insert(5);
mylist.Insert(9);
mylist.display();
system("PAUSE");
return 0;
}
答案 0 :(得分：8)
您的List::Insert(const int value)方法根本不会调用List复制构造函数，它只会在intptr数组内写入。当count大于size时，您会在数组外写字，这就是您遇到错误的原因。
您应该将复制构造函数中的操作直接移动到Insert方法。
答案 1 :(得分：1)
您没有正确管理数组，尤其是在Insert()方法中。试试这个：
#include "list.h" // Include our Class defintion
#include <iostream>
// CONSTRUCTOR
List::List()
{
intptr = new int[2];
size = 2;
count = 0;
std::cout << "Initial size : " << size << " count : " << count << std::endl;
}
// DECONSTRUCTOR
List::~List()
{
delete [] intptr; // free allocated memory
}
// Copy constructor
List::List(const List& value)
{
intptr = new int[value.size]; // Allocate new data
size = value.size;
count = value.count;
for(int index = 0; index < count; ++index)
intptr[index] = value.intptr[index];
std::cout << "Copy size : " << size << " count : " << count << std::endl;
}
void List::Insert(const int value)
{
if (count == size)
{
int *newintptr = new int[size+2];
for(int index = 0; index < size; ++index)
newintptr[index] = intptr[index];
delete[] intptr;
intptr = newintptr;
size += 2;
}
intptr[count] = value;
++count;
std::cout << "New size : " << size << " count : " << count << std::endl;
}
void List::display() const
{
for(int i = 0; i < count; i++)
std::cout << intptr[i] << std::endl;
}
#include <iostream>
#include "list.h"
int main()
{
List mylist;
mylist.Insert(5);
mylist.Insert(6);
mylist.Insert(2);
mylist.Insert(8);
mylist.Insert(4);
mylist.Insert(5);
mylist.Insert(9);
mylist.Insert(8);
mylist.Insert(5);
mylist.Insert(9);
mylist.Insert(8);
mylist.Insert(5);
mylist.Insert(9);
mylist.Insert(8);
mylist.Insert(5);
mylist.Insert(9);
mylist.display();
system("PAUSE");
List mylist2(myList); // copy construct a new list
mylist2.display();
system("PAUSE");
return 0;
}
话虽如此，你真的应该使用std::vector代替，例如：
#include <iostream>
#include <vector>
#include <algorithm>
void displayValue(int value)
{
std::cout << value << std::endl;
}
int main()
{
std::vector<int> mylist;
mylist.push_back(5);
mylist.push_back(6);
mylist.push_back(2);
mylist.push_back(8);
mylist.push_back(4);
mylist.push_back(5);
mylist.push_back(9);
mylist.push_back(8);
mylist.push_back(5);
mylist.push_back(9);
mylist.push_back(8);
mylist.push_back(5);
mylist.push_back(9);
mylist.push_back(8);
mylist.push_back(5);
mylist.push_back(9);
std::for_each(mylist.begin(), myList.end(), displayValue);
system("PAUSE");
std::vector<int> myList2(myList);
std::for_each(mylist2.begin(), myList2.end(), displayValue);
system("PAUSE");
return 0;
}
更进一步，如果您想继续使用自定义List课程，请至少在其中使用std::vector：
#include <vector>
class List
{
public:
// DEFAULT Constructor
List();
//Modification methods
void Insert(const int);
// User ACCESS methods
void display(void) const;
protected:
std::vector<int> intvec;
};
#include "list.h" // Include our Class defintion
#include <iostream>
// CONSTRUCTOR
List::List()
{
intvec.reserve(2);
std::cout << "Initial size : " << intvec.capacity() << " count : " << intvec.size() << std::endl;
}
// Copy constructor
List::List(const List& value)
{
intvec = value.intvec;
std::cout << "Copy size : " << invec.capacity() << " count : " << intvec.size() << std::endl;
}
void List::Insert(const int value)
{
intvec.push_back(value);
std::cout << "New size : " << intvec.capacity() << " count : " << intvec.size() << std::endl;
}
void List::display() const
{
for(std::vector<int>::const_iterator iter = intvec.begin(), end = intvec.end(); iter != end; ++iter)
std::cout << *iter << std::endl;
}
#include <iostream>
#include "list.h"
int main()
{
List mylist;
mylist.Insert(5);
mylist.Insert(6);
mylist.Insert(2);
mylist.Insert(8);
mylist.Insert(4);
mylist.Insert(5);
mylist.Insert(9);
mylist.Insert(8);
mylist.Insert(5);
mylist.Insert(9);
mylist.Insert(8);
mylist.Insert(5);
mylist.Insert(9);
mylist.Insert(8);
mylist.Insert(5);
mylist.Insert(9);
mylist.display();
system("PAUSE");
List mylist2(myList); // copy construct a new list
mylist2.display();
system("PAUSE");
return 0;
}
答案 2 :(得分：1)
copy-constructor的原因是从现有对象创建一个新对象，但是看看你的copy-constructor，你在那里做什么？
/* initialize my size and count, from value */
size = value.size;
count = value.count;
/* Check count and size */
if( count == size ) /* if other is full */
size += 2;
/* copy content from value.intptr into this->intptr */
//if (count < size)
// intptr = new int[size]; // Allocate new data
//else
// intptr = new int[size + 2]; // Allocate new data
intptr = new int[size]; /* Allocate my buffer */
/* It's better to use std::copy in place of a hand written loop */
//for(int index = 0; index < count; index++)
// intptr[index] = value.intptr[index];
std::copy( value.intptr, value.intptr + value.count, intptr );
/* why you increase your size here?? shouldn't this indicate size of intptr? */
//size = size + 2;
/* After creating a new buffer and putting data into it, you destroy the buffer
and set your buffer equal to buffer of value? why? if value destroyed it will
destroy its intptr and your intptr point to a deleted memory
*/
//delete [] intptr;
// intptr = value.intptr;
现在看看你的insert方法：
if(count < size) // do we have room?
{
intptr[count] = value;
}
else // if not we need to add more elements to array
{
/* As you already checked you do not have enough room to insert data to intptr
so why you do it here? shouldn't you first allocate a new buffer and then
copy data to it?
In comment you say DEEP copy with copy-constructor, which copy constructor
you expect to called here? you are assigning an int to another int, so where
is copy constructor?
*/
// intptr[count] = value; // DEEP copy invoked with copy constructor
int* tmp = new int[size + 2];
std::copy( intptr, intptr + size, tmp );
delete[] intptr;
intptr = tmp;
size += 2;
intptr[count] = value;
}
count++; // Increase items added in array
答案 3 :(得分：-1)
使用std :: vector。它已经完成了所有这些工作，并且比代码更安全，更快速。