重载算术运算符C++

我必须执行以下操作：

在Cash.h中，在Money命名空间内为+操作的运算符重载添加一个声明；这应该采用两个CCD_ 4操作数并返回一个新的CCD_。请记住，声明将由结果类型(Cash(、操作名称(operator +(和两个参数((Cash a, Cash b((组成，后跟一个分号。

在Cash.cpp中，在Money命名空间中添加运算符的定义。此定义应创建并返回一个新的Cash值，该值的a.cents()和b.cents()的总和作为其cents()值。如果a和b的面额不同，您需要选择一种与两者均匀匹配的面额；Cash.cpp包含一个函数gcf，您可以使用它来确定适合的最大值(对于此分配，您不必保证它代表实际流通的硬币(。

注意：我无法编辑solution.cpp

//Cash.cpp
#include "Cash.h"
#include <cstdlib>
#include <utility>
#include <iostream>
int gcf(int a, int b)
{
using std::swap;
if (abs(a) < abs(b)) { swap(a, b); }
if (b == 0) { return a; }
a %= b;
return a == 0? b: gcf(b, a);
}
namespace Money {
Cash::Cash(int d, int c)
: _count{c}, denomination{d} 
{
if (_count < 0 || denomination <= 0) {
std::cerr << "Cash object constructed with invalid currency count.n";
}
}
// only code I can edit in this file, rest is locked
const Cash operator + (const Cash& a, const Cash& b){
Cash cents();
cents() = a.cents() + b.cents();
return cents();
};    
}

//Cash.h
#pragma once
#ifndef MONEY_CASH
#define MONEY_CASH
namespace Money {
class Cash {
public:
Cash(): Cash{1, 0} {}
Cash(int d, int c);
Cash(const Cash& other): Cash{other.denomination, other._count} {}
int count() const { return _count; }
int cents() const { return _count * denomination; }
const int denomination;
private:
int _count;
};
// only code I can edit in this file, rest is locked
const Cash operator + (const Cash& a, const Cash& b);
}
#endif

//Solution.cpp
#include <iostream>
#include "Cash.h"
int main(int argc, char* argv[])
{
using namespace std;
using namespace Money;
int D, N;
cin >> D >> N;
Cash a {D, N};
cin >> D >> N;
Cash b {D, N};
Cash c = a + b;
cout << "Result: " << c.cents() << " cents in " << c.denomination << "s.";
return 0;
}

使用此当前代码，我得到以下错误：

./Cash.cpp: In function 'const Money::Cash Money::operator+(const Money::Cash&, const Money::Cash&)':
./Cash.cpp:28:39: error: no match for 'operator=' (operand types are 'Money::Cash' and 'int')
cents() = a.cents() + b.cents();
^
In file included from ./Cash.cpp:1:
./Cash.h:7:11: note: candidate: 'Money::Cash& Money::Cash::operator=(const Money::Cash&)' <deleted>
class Cash {
^~~~
./Cash.h:7:11: note:   no known conversion for argument 1 from 'int' to 'const Money::Cash&'