程序填空题：跨币种转账 - C/C++ 隐藏的实现

AccountCNY类表示人民币账户，AccountUSD类表示美元账户，账户余额为私有数据成员。a.transfer(b,100)表示从a账户转出100元（a账户币种）至b账户。当a和b账户的币种相同时，a的余额减少100，b的余额增加相同值；当a、b账户币种不同时，a的余额减少100，但b的余额增加值应进行汇率换算。<br>
请将下述代码补充完整，使其能正常运行。假设汇率为1美元兑6.5元人民币。
c++
#include <iostream>
#include <stdio.h>
using namespace std;

class AccountUSD;
class AccountCNY {
private:
double dBalance {0};
public:
void deposit(double fAmount){ //存款函数

}

double balance(){
return dBalance;
}

bool transfer(AccountCNY& b, double fAmount){
if (dBalance < fAmount)
return false;
dBalance -= fAmount;
b.dBalance +=
return true;
}

bool transfer(, double fAmount);
friend
};

class AccountUSD {
private:
double dBalance {0};
public:
void deposit(double fAmount){

}

double balance(){
return dBalance;
}

bool transfer(AccountUSD& b, double fAmount){
if (dBalance < fAmount)
return false;

b.dBalance += fAmount;
return true;
}

bool transfer(AccountCNY& b, double fAmount);
friend
};

bool AccountCNY::transfer(AccountUSD& b, double fAmount){
if (dBalance < fAmount)
return false;
dBalance -= fAmount;
b.dBalance +=
return true;
}

bool AccountUSD::transfer(AccountCNY& b, double fAmount){
if (dBalance < fAmount)
return false;
dBalance
b.dBalance +=
return true;
}

int main()
{
AccountCNY a, b;
a.deposit(1000); b.deposit(1000);
printf("Deposit CNY 1000 to a & b\n");
printf("CNY Account a: %.2f\n",a.balance());
printf("CNY Account b: %.2f\n",b.balance());

AccountUSD c,d;
c.deposit(1000); d.deposit(1000);
printf("Deposit USD 1000 to c & d\n");
printf("USD Account c: %.2f\n",c.balance());
printf("USD Account d: %.2f\n",d.balance());

a.transfer(b,100);
printf("Transfer CNY 100 from a --> b\n");
printf("CNY Account a: %.2f\n",a.balance());
printf("CNY Account b: %.2f\n",b.balance());

c.transfer(d,100);
printf("Transfer USD 100 from c --> d\n");
printf("USD Account c: %.2f\n",c.balance());
printf("USD Account d: %.2f\n",d.balance());

a.transfer(d,650);
printf("Transfer CNY 650 from a --> d\n");
printf("CNY Account a: %.2f\n",a.balance());
printf("USD Account d: %.2f\n",d.balance());

c.transfer(a,100);
printf("Transfer USD 100 from c --> a\n");
printf("USD Account c: %.2f\n",c.balance());
printf("CNY Account a: %.2f\n",a.balance());

return 0;
}


请注意：函数题只需要提交相关代码片段，不要提交完整程序。


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答案：
第1空：dBalance += fAmount;

第2空：fAmount;

第3空：AccountUSD& b

第4空：class AccountUSD;

第5空：dBalance += fAmount;

第6空：dBalance -= fAmount;

第7空：class AccountCNY;

第8空：fAmount/6.5;

第9空：-= fAmount;

第10空：fAmount*6.5;