打印操作员超载失败？
我在练习C ++基本继承概念时，遇到了打印出一个自定义类对象并写入一个过载的需求，完全按照指导原则进行，但仍未注册使用新操作符进行打印（<<）。
我想知道是否输入错误或在其他地方有一些声明/启动错误？
'operator <<'没有匹配（操作数类型是'std :: basic_ostream'和'Choco'）std :: cout <<“Choco value：”<< child << endl;
#include <iostream>
using namespace std;
class Sweets {
public:
// pure virtual, child MUST implement or become abstract
// Enclosing class becomes automatically abstract - CANNOT instantiate
virtual bool eat() = 0;
};
// public inheritance : public -> public, protected -> protected, private only accessible thru pub/pro members
class Choco : public Sweets {
public:
bool full;
Choco() {
full = false;
}
// Must implement ALL inherited pure virtual
bool eat() {
full = true;
}
// Overload print operator
bool operator<<(const Choco& c) {
return this->full;
}
};
int main() {
// Base class object
//sweets parent;
Choco child;
// Base class Ptr
// Ptr value = address of another variable
Sweets* ptr; // pointer to sweets
ptr = &child;
std::cout<< "Sweets* value: " << ptr << endl;
std::cout<< "Choco address: " << &child << endl;
std::cout<< "Choco value: " << child << endl; // Printing causes error!
}
因为它不是类成员，所以在类之外定义了以下方式。
std::ostream & operator <<( std::ostream &os, const Choco &c )
{
return os << c.full;
}
考虑到该功能
bool eat() {
full = true;
}
应该有一个带有bool类型表达式的return语句，或者应该在基类和派生类中用返回类型void声明它。