如何在 C++ 中打印第一个和第二个 2 类 的向量对?
How to print a vector of pairs that have as first and second 2 classes in c++?
我有这样的东西,其中客户和订单是 类 :
std::vector<std::pair<Client,Order>> pair;
pair.push_back(std::make_pair(Client(2,"Anca"),Order(3,1)));
pair.push_back(std::make_pair(Client(16,"Maria"),Order(1,3)));
pair.push_back(std::make_pair(Client(29,"Alex"),Order(10,5)));
class Client{
private:
int dateWhenOrderWasPlaced;
std::string clientName;
public:
Client(int date,std::string name){
dateWhenOrderWasPlaced=date;
clientName=name;
}
class Order{
private:
int amountPizza;
int pizzaAge;
public:
Order(int amPizza,int agePizza){
amountPizza=amPizza;
pizzaAge=agePizza;
}
而且我不知道如何打印 this.I 尝试了很多方法:
void print(std::vector<std::pair<Client,Order>> pair){
for(const auto& it : pair){
std::cout << "First: "<<pair[it].first<< ", Second: " << pair[it].second <<std::endl;
}
}
还有这个:
void print(std::vector<std::pair<Client,Order>> pair){
for(const auto& it : pair){
std::cout << "First: "<<it.first<< ", Second: " << it.second <<std::endl;
}
}
并且在这两种方式中我都有错误(第一个是没有运算符[],第二个是没有运算符<<)
您的第一次尝试没有成功,因为 it
是实际的一对,但 std::pair
没有 operator[]
。您的第二次尝试是正确的方法,但它不起作用,因为您没有为 类.
定义 operator<<
所以,简单定义operator<<
,例如:
class Client
{
private:
int dateWhenOrderWasPlaced;
std::string clientName;
public:
Client(int date, std::string name)
: dateWhenOrderWasPlaced(date), clientName(name)
{
}
friend std::ostream& operator<<(std::ostream &os, const Client &c)
{
// print c.dateWhenOrderWasPlaced and c.clientName to os as needed...
return os;
}
};
class Order
{
private:
int amountPizza;
int pizzaAge;
public:
Order(int amPizza, int agePizza)
: amountPizza(amPizza), pizzaAge(agePizza)
{
}
friend std::ostream& operator<<(std::ostream &os, const Order &o)
{
// print o.amountPizza and o.pizzaAge to os as needed...
return os;
}
};
void print(const std::vector<std::pair<Client,Order>> &pair)
{
for(const auto& it : pair)
{
std::cout << "First: " << it.first << ", Second: " << it.second << std::endl;
}
}
我有这样的东西,其中客户和订单是 类 :
std::vector<std::pair<Client,Order>> pair;
pair.push_back(std::make_pair(Client(2,"Anca"),Order(3,1)));
pair.push_back(std::make_pair(Client(16,"Maria"),Order(1,3)));
pair.push_back(std::make_pair(Client(29,"Alex"),Order(10,5)));
class Client{
private:
int dateWhenOrderWasPlaced;
std::string clientName;
public:
Client(int date,std::string name){
dateWhenOrderWasPlaced=date;
clientName=name;
}
class Order{
private:
int amountPizza;
int pizzaAge;
public:
Order(int amPizza,int agePizza){
amountPizza=amPizza;
pizzaAge=agePizza;
}
而且我不知道如何打印 this.I 尝试了很多方法:
void print(std::vector<std::pair<Client,Order>> pair){
for(const auto& it : pair){
std::cout << "First: "<<pair[it].first<< ", Second: " << pair[it].second <<std::endl;
}
}
还有这个:
void print(std::vector<std::pair<Client,Order>> pair){
for(const auto& it : pair){
std::cout << "First: "<<it.first<< ", Second: " << it.second <<std::endl;
}
}
并且在这两种方式中我都有错误(第一个是没有运算符[],第二个是没有运算符<<)
您的第一次尝试没有成功,因为 it
是实际的一对,但 std::pair
没有 operator[]
。您的第二次尝试是正确的方法,但它不起作用,因为您没有为 类.
operator<<
所以,简单定义operator<<
,例如:
class Client
{
private:
int dateWhenOrderWasPlaced;
std::string clientName;
public:
Client(int date, std::string name)
: dateWhenOrderWasPlaced(date), clientName(name)
{
}
friend std::ostream& operator<<(std::ostream &os, const Client &c)
{
// print c.dateWhenOrderWasPlaced and c.clientName to os as needed...
return os;
}
};
class Order
{
private:
int amountPizza;
int pizzaAge;
public:
Order(int amPizza, int agePizza)
: amountPizza(amPizza), pizzaAge(agePizza)
{
}
friend std::ostream& operator<<(std::ostream &os, const Order &o)
{
// print o.amountPizza and o.pizzaAge to os as needed...
return os;
}
};
void print(const std::vector<std::pair<Client,Order>> &pair)
{
for(const auto& it : pair)
{
std::cout << "First: " << it.first << ", Second: " << it.second << std::endl;
}
}