c++ - 未定义模板 'std::__1::vector 的隐式实例化' 错误

Question

我正在尝试将类的指针存储在向量中，但出现错误

未定义模板 'std::__1::vector<Item *>' 的隐式实例化

代码是：

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

class Item{
private:
    string itemName;
    float itemPrice;
    int itemQuantity;
public:
    Item(string name = "NULL", float price = 0, int quantity = 0){
        
        itemName = name;
        itemPrice = price;
        itemQuantity = quantity;
    
        
    }
    friend ofstream & operator<<(ofstream &ofs, Item &i);
    friend ifstream & operator>>(ifstream &ifs, Item &i);
    friend ostream & operator<<(ostream &os, Item &i);
    

};

ofstream & operator<<(ofstream & ofs, Item &i){
    
    ofs << i.itemName << endl;
    ofs << i.itemPrice << endl;
    ofs << i.itemQuantity << endl;
    return ofs;
    
    
    
    
}

ostream & operator<<(ostream &os, Item &i){

    os << i.itemName << endl;
    os << i.itemPrice << endl;
    os << i.itemQuantity << endl;
    
    return os;
}

ifstream & operator>>(ifstream & ifs , Item & i){
    ifs >> i.itemName;
    ifs >> i.itemPrice;
    ifs >> i.itemQuantity;
    
    return ifs;
    
    
}
int main() {
int n;
string name;
float price;
int qty;
cout<<"Enter number of Item:";
cin>>n;
vector<Item *> items;
cout<<"Enter All Item "<<endl;
for(int i=0;i<n;i++)
{
    cout<<"Enter "<<i+1<<" Item Name , price and quantity";
    cin>>name;
    cin>>price;
    cin>>qty;
    items.push_back(new Item(name,price,qty));
}
ofstream fos("Items.txt");
for(int i=0;i<n;i++)
{
    fos<<*items[i];
}
Item item;
ifstream fis("Items.txt");
for(int i=0;i<3;i++)
{
    fis>>item;
    cout<<"Item "<<i<<item<<endl;
}
}

它看起来像一个基本错误，但我找不到解决方法。如何将用户定义类的指针存储在向量中？我的语法是关闭的还是向量不能那样工作？

标签： c++pointersvector

Answer 1

你没有包括

#include <vector>

添加它，您的代码将编译干净。