问题描述
我试图在我的向量中添加一个客户，当我运行程序时，将调用复制构造函数。我正在做一个分配工作，我需要一个向量客户，并且必须能够添加客户，显示客户，查找客户以及加载/存储数据。我创建的矢量错误吗？我只是c ++的新手，真的不确定矢量。
Main.cpp中的代码：
#include <iostream>
#include <fstream>
#include <string>
#include <sstream>
#include <vector>
#include "Customer.h"
using namespace std;
void OutputFileStream();
void parseLine(const string& str);
void InputFileStream();
void save(vector<Customer> customers);
void load(vector<Customer>& customers);
void addCustomer(vector<Customer>& vect);
void displayAll(vector<Customer>& customers);
//void printActions();
vector<Customer> customers;
void OutputFileStream()
{
cout << "Creating and writing to file: Customer.txt" << endl;
ofstream outStream("customers.txt"); // write mode (overwrites existing data)
if (outStream.good())
{
int customerID = 150033;
outStream << "This is a line of text.\n";
outStream << "This is another line of text.\n";
outStream << "This is a line of text.\n";
int numOfPurchases = 4;
int purchases = 0;
outStream << customerID << "Mr" << "Jack" << "New" << numOfPurchases << purchases << endl;
//int *purchases = customers[0].getPurchases();
outStream.close(); // close file
cout << "File written.\n" << endl;
}
else
cout << "Unable to open file";
}
void parseLine(const string& str) {
stringstream strStream(str); //create string stream from the string
// int customerID;
string title;
string name;
string type;
//int numOfPurchases;
//int purchases;
string s;
int customerID = 150033;
getline(strStream,s,';');
customerID = stoi(s);
getline(strStream,title,';');
getline(strStream,name,type,';');
int numOfPurchases = 4;
getline(strStream,';');
numOfPurchases = stoi(s);
int purchases = 0;
getline(strStream,';');
purchases = stoi(s);
int* purchasesArray = new int[3];
purchasesArray[0] = (purchases & (255 << 16)) >> 16;
purchasesArray[1] = (purchases & (255 << 8)) >> 8;
purchasesArray[2] = purchases & 255;
for (int i = 0; i < 3; i++)
{
cout << purchasesArray[i];
}
cout << " CustomerID: " << customerID << "Title:" << title << " Name: " << name << " Type:" << type << " Number of Purchases: " << numOfPurchases << "Purchases: " << purchases << endl;
}
void InputFileStream() {
cout << "Reading from a semi-colon delimited txt file" << endl;
string line;
ifstream inStream("customers.txt"); //opens file as an input file stream
if (inStream.good()) //if the file is opened successfully and not empty
{
while (getline(inStream,line)) //reads line until false return
{
parseLine(line);
}
inStream.close();
}
else
cout << "unable to open file or the file is empty!";
}
void save(vector<Customer> customers)
{
ofstream out("customers.txt");
if(out)
{
for (Customer& c : customers)
{
out << c.save();
}
out.flush();
out.close();
}
else
{
cout << "Error Writing to File" << endl;
}
}
void load(vector<Customer>& customers)
{
ifstream in("customers.txt");
if (in) {
string line;
while (!in.eof())
{
getline(in,line);
if (line != "")
{
Customer c;
c.parse(line);
customers.push_back(c);
}
}
}
}
void addCustomer(vector<Customer>& customers) {
Customer customer;
cin >> customer;
customers.push_back(customer);
}
void displayAll(vector<Customer>& customers)
{
cout << "\nvector contains:\n";
for (Customer c : customers)
cout << c.getCustomerID() << " " << c.getTitle() << c.getName() << c.getNumOfPurchases() << c.getPurchases() << c.getType() << endl;
cout << endl;; //same as calling customer
}
//
//int getCustomerByPurchaseNumber(int numOfPurchases) {
// vector<Customer> customers;
// int pos = -1;
// for (int i = 0; i < customers.size(); i++) {
// if (customers.at(i).getNumOfPurchases() == numOfPurchases) {
// return i;
// }
// }
// return pos;
//}
//
//void findCustomerByPurchaseNumber(vector<Customer>& customers) {
// vector<Customer> customers;
// int numOfPurchases;
// cout << "Please Enter Your Purchase Number:" << endl;
// cin >> numOfPurchases;
// int pos = customers.get(pos);
// getCustomerByPurchaseNumber(numOfPurchases);
// if (pos == -1) {
// cout << "Number of Purchase Not Found! " << endl;
// return customers;
// }
// else {
// cout << "Number Of Purchase Found! " << endl;
//
// return customers* = customers;
// }
//
//}
int main()
{
vector<Customer> customers;
Customer c1 = { 150031,"Mr","John",5,333,362,341,"New" };
customers.push_back(c1);
//InputFileStream();
/* Customer customer;
customer.setCustomerID(150032);
customer.setTitle("Mr");
customer.setName("Joey");
customer.setNumOfPurchases(3);
customer.setPurchases(366,352,334);
customer.setType("New");
cout << customer.getCustomerID() << endl;
cout << customer.getTitle() << endl;
cout << customer.getName() << endl;
cout << customer.getNumOfPurchases() << endl;
cout << customer.getPurchases() << endl;
cout << customer.getType() << endl;
*/
return 0;
}
Customer.cpp中的代码：
#include "Customer.h"
#include <iostream>
#include <string>
#include <fstream>
#include <sstream>
#include<utility>
using namespace std;
//default constructor
Customer::Customer() {
}
//Full constructor
Customer::Customer(int customerID,string title,string name,int numOfPurchases,int purchase1,int purchase2,int purchase3,string type)
{
this->customerID = customerID;
this->title = title;
this->name = name;
this->numOfPurchases = numOfPurchases;
purchases = new int[3];
purchases[0] = purchase1;
purchases[1] = purchase2;
purchases[2] = purchase3;
this->type = type;
}
Customer::Customer(const Customer& source) //copy constructor
{
cout << "copy constructor called" << endl;
this->customerID = source.customerID;
this->title = source.title;
this->name = source.name;
this->numOfPurchases = source.numOfPurchases;
this->purchases = new int[3];
purchases[0] = source.purchases[0];
purchases[1] = source.purchases[1];
purchases[2] = source.purchases[2];
this->type = source.type;
}
//overloaded assignment operator=
Customer& Customer::operator= (Customer& otherCustomer)
{
cout << "Overloaded assignment operator= called" << endl;
//self-assignment guard
if (this == &otherCustomer)
return *this; //refernce to the same object
// copy data from the source (rhs) to this object (the destination)
name = otherCustomer.name;
//must make a new scores object to store a copy of the other student
if (purchases != nullptr)
delete[] purchases;
purchases = new int[3];
for (int i = 0; i < 3; i++) {
purchases[i] = otherCustomer.purchases[i];
}
//return this existing object so we can chain this operator
return *this;
}
string Customer::save()
{
stringstream out;
out << this->customerID << ";";
out << this->title << ";";
out << this->name << ";";
out << this->type << ";\n";
out << this->numOfPurchases << ";";
int* purchases = 0;
out.flush();
return out.str();
}
void Customer::parse(string line)
{
stringstream in(line);
string customerIDLine;
getline(in,customerIDLine,';');
customerID = stoi(customerIDLine);
getline(in,';');
getline(in,';');
string numOfPurchases;
getline(in,numOfPurchases,';');
int s = stoi(numOfPurchases);
int* purchasesArray = new int[3];
purchasesArray[0] = (s & (255 << 16)) >> 16;
purchasesArray[1] = (s & (255 << 8)) >> 8;
purchasesArray[2] = s & 255;
}
void Customer::addCustomer(vector<Customer>& customers )
{
//after read data
int customerID;
cout << "Please Enter Customer ID: " << endl;
cin >> customerID;
string title;
cout << "Please Enter Title: " << endl;
getline(cin,title);
string name;
cout << "Please Enter Name: " << endl;
getline(cin,name);
string type;
cout << "Please Enter Type: " << endl;
getline(cin,type);
int numOfPurchases;
cout << "Please Enter Number of Purchases: " << endl;
cin >> numOfPurchases;
int purchase1;
cout << "Please Enter First Purchase: " << endl;
cin >> purchase1;
int purchase2;
cout << "Please Enter Second Purchase: " << endl;
cin >> purchase2;
int purchase3;
cout << "Please Enter Third Purchase: " << endl;
cin >> purchase3;
Customer c;
customers.push_back(c);
//Customer c();
}
Customer::~Customer() {
cout << "Destructor ~Customer called" << endl;
delete[] purchases;
}
// Overloaded insertion operator (Outputs Character object data as an output stream)
// Defined in header file as a "friend" function,as it is not a member function
//
ostream& operator<<(ostream& out,Customer& customer)
{
cout << "Customer details ( output by insertion operator<< )" << endl;
cout << "Customer ID: " << customer.customerID << endl;
cout << "Title: " << customer.title << endl;
cout << "Name: " << customer.name << endl;
cout << "Number of purchases: " << customer.numOfPurchases << endl;
cout << "Purchases: ";
for (int i = 0; i < 3; i++)
{
if (i > 0) cout << ",";
cout << customer.purchases[i];
}
cout << "Type: " << customer.type << endl;
return out;
}
istream& operator>> (istream& in,Customer& customer)
{
cout << "Enter Customer details ( using the extraction operator>> )" << endl;
cout << "Enter Customer ID: " << endl;
cin >> customer.customerID;
cout << "Enter Title: " << endl;
getline(cin,customer.title);
cout << "Enter Name: " << endl;
getline(cin,customer.name);
cout << "Enter Number of Purchases: ";
cin >> customer.numOfPurchases;
cout << "Enter Purchases: ";
cin >> customer.purchases[0];
cin >> customer.purchases[1];
cin >> customer.purchases[2];
cout << "Enter Type";
getline(cin,customer.type);
cout << endl;
return in;
}
int Customer::getCustomerID()
{
return customerID;
}
string Customer::getTitle()
{
return title;
}
string Customer::getName()
{
return name;
}
int Customer::getNumOfPurchases()
{
return numOfPurchases;
}
int* Customer::getPurchases()
{
return purchases;
}
string Customer::getType()
{
return type;
}
void Customer::setCustomerID(int customerID)
{
if (customerID < 1) {
cout << "Customer ID has to be equal to 1 or more" << endl; //Changed all the "throw invalid_argument" messages to cout as they were causing an issue with my main.cpp file and an abort message kept appearing every time I ran my main.cpp file.
}
this->customerID = customerID;
}
void Customer::setTitle(string title)
{
if (title.length() < 2) {
cout << "Title has to be more than or equal to 2 characters" << endl;
}
this->title = title;
}
void Customer::setName(string name)
{
if (name.length() < 4) {
cout << "Length of name should be more than or equal to 4 characters" << endl;
}
this->name = name;
}
//Got help ith this on stack overflow as I was using "&&" instead of using "||" for the if statement
void Customer::setNumOfPurchases(int numOfPurchases)
{
if(numOfPurchases <0 || numOfPurchases > 10000){
cout << "Number of purchases should be between 0 to 10000" << endl;
}
this->numOfPurchases = numOfPurchases;
}
void Customer::setPurchases(int purchase1,int purchase3)
{
if (purchase1 < 0 || purchase2 < 0 || purchase3 < 0) {
cout << "Purchases must be more than or equal to zero" << endl;
}
}
//Got help from stack overflow on comparing strings as I originally didnt use "type.compare"
void Customer::setType(string type) {
if (type.compare("New") !=0 || type.compare("Either") !=0) {
cout << "Type of purchase has to be New or Either" << endl;
}
}
Customer.h中的代码：
#pragma once
#include<iostream>
using namespace std;
#include<string>
#include <vector>
class Customer
{
private:
int customerID;
string title;
string name;
int numOfPurchases;
int* purchases;
string type;
public:
Customer(); // default constructor
Customer(int customerID,string type);
//copy overload assignment
Customer& operator=(Customer& otherCustomer);
Customer(const Customer& source);
string save();
void parse(string line);
void addCustomer(vector<Customer>& customers);
~Customer(); //destructor
//Getters and Setters
void setCustomerID(int customerID);
void setTitle(string title);
void setName(string name);
void setNumOfPurchases(int numOfPurchases);
void setPurchases(int purchase1,int purchase3);
void setType(string type);
int getCustomerID();
string getTitle();
string getName();
int getNumOfPurchases();
int* getPurchases();
string getType();
void printCustomer() {
cout << customerID << "," << title << "," << name << "," << numOfPurchases << "," << purchases << "," << type << endl;
}
friend std::ostream& operator<<(std::ostream& out,Customer& customer); // overloaded operator<<
friend istream& operator>> (istream& in,Customer& customer); // overloaded operator >>
};
解决方法
向量保存对象。如果矢量之外有对象，则无法在矢量内包含同一对象。您可以在向量中从一个实例移动到另一个实例（这将使实例内部移动，但仍然有两个实例）。 push_back确实会在其参数无法移出时对其参数进行复制。
由于您有一个采用所有必要参数的构造函数，因此可以使用emplace_back来避免复制并在向量中就位构造实例：
customers.emplace_back( customerID,title,name,numOfPurchases,purchase1,purchase2,purchase3,type);
std::vector<Customer>按值保存元素，因此仅使用std::vector::push_back会将您的本地对象复制到向量中。
为减轻这种情况，您可以实现移动语义并像这样移动Customer对象：
#include <utility>
....
Customer c;
c.parse(line);
customers.push_back(std::move(c));
或就地构建对象：
// Post c++17 you could use `push_back()` here as well as
// c++17 has mandatory copy elision.
customers.emplace_back(Customer{}); // or customers.emplace_back(); only
customers.back().parse(line);
两个解决方案都需要c ++ 11。
您还可以存储引用/指针并在堆上分配对象。
std::vector<std::unique_ptr<Customer>> customerVector;
customer_vector.push_back(std::make_unique<Customer>());
// or customer_vector.push_back(std::make_shared<Customer>());
或
std::vector<Customer*> customerVector;
// Beware for memory leaks,needs to be deleted.
// Basically never use code like this post c++11).
customer_vector.push_back(new Customer{});
如果您选中std::vector<T,Allocator>::push_back上的引用，则可以通过复制（选项1）或移动（选项2）将其添加到矢量中。
因此，您可以为客户类别创建move constructor：
class_name ( class_name && );
然后在向量上使用该移动构造函数（选项2）调用push_back ：
void push_back( T&& value );