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我试图编写一个程序，将密码限制为 3 次错误尝试，然后在 3 次错误尝试后退出。这是我到目前为止的代码。我觉得我真的很接近解决这个问题，但我不知道该怎么做。

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

void getPassword() 
{ 
  for(int i = 0; i < 3; i++)
  {
    string password; 
    cout << "Enter the password: "; 
    getline(cin, password); 

    if (password == "12345") break; 
      cout << "INVALID. "; 
  } //for
} // getPassword 
int main ()
{
  if (!getPassword()) break;
  else break;
  cout <<endl; 

  ofstream fout; 
  fout.open("mort.txt", ios::app);
  if (!fout.good()) throw "I/O error";

  double p; //Principal/Mortgage Amount
  cout << "What's the mortgage amount?";
  cin >> p; 
  cin.ignore (1000, 10);

  double r; 
  cout << "What's the annual interest rate?";
  cin >> r ;
  cin.ignore (1000, 10);
  double a = r / 100;
  double i = a / 12;

  double n = 30 * 12; //Number of payments per month
  double t = (p*(pow (1+i, n))*i) / ((pow(1+i, n)) -1);// monthly payment formula 

  cout<< fixed;
  cout<< setprecision(2);

  cout << "Mortgage Amount: "<<"$"<< p <<endl;
  cout << "Interest Rate: "<< r <<"%"<<endl;
  cout << "Term Years: "<< "30 " << "Years" <<endl;
  cout << "Monthly Payment: " <<"$"<< t <<endl; 

  fout << "Mortgage Amount: "<<"$"<< p <<endl;
  fout << "Interest Rate: "<< r <<"%"<<endl;
  fout << "Term Years: "<< "30 " << "Years" <<endl;
  fout << "Monthly Payment: " <<"$"<< t <<endl;
  fout <<endl; 

  fout.close();
  return 0; 
}
4

1 回答 1

5

如果密码输入正确（在 if 语句中），则返回布尔值，而不是使用 void 函数，如果 3 次尝试失败（在循环之后），则返回 false。然后在您的主函数中根据需要处理 getPassword 返回的内容。

所以像

#include <fstream>
#include <iomanip>
#include <iostream>
#include <string>

using namespace std;
#include <cmath>
bool getPassword() 
{ 
    for(int i = 0; i < 3; i++)
    {
    string password; 
    cout << "Enter the password: "; 
    getline(cin, password); 

    if (password == "12345") return true; 
    cout << "INVALID. "; 
     } //for
return false;
} // getPassword 

int main ()
{
  if (!getPassword()) return 1;
  cout <<endl; 

  ofstream fout; 
  fout.open("mort.txt", ios::app);
  if (!fout.good()) throw "I/O error";

  double p; //Principal/Mortgage Amount
  cout << "What's the mortgage amount?";
  cin >> p; 
  cin.ignore (1000, 10);

  double r; 
  cout << "What's the annual interest rate?";
  cin >> r ;
  cin.ignore (1000, 10);
  double a = r / 100;
  double i = a / 12;

  double n = 30 * 12; //Number of payments per month
  double t = (p*(pow (1+i, n))*i) / ((pow(1+i, n)) -1);// monthly payment formula 

  cout<< fixed;
  cout<< setprecision(2);


  cout << "Mortgage Amount: "<<"$"<< p <<endl;
  cout << "Interest Rate: "<< r <<"%"<<endl;
  cout << "Term Years: "<< "30 " << "Years" <<endl;
  cout << "Monthly Payment: " <<"$"<< t <<endl; 


  fout << "Mortgage Amount: "<<"$"<< p <<endl;
  fout << "Interest Rate: "<< r <<"%"<<endl;
  fout << "Term Years: "<< "30 " << "Years" <<endl;
  fout << "Monthly Payment: " <<"$"<< t <<endl;
  fout <<endl; 

  fout.close();
  return 0; 
}
于 2011-12-08T23:09:18.640 回答