Question

#include "stdafx.h"
#include <iostream>
#include <string>

using std::cout;
using std::cin;
using std::endl;
using std::exit;
using std::string;

void pin(double &Balance);
void menu(double &Balance);
void helpMenu();
void withdraw(double &Balance);
void deposit(double &Balance);
void overdraft(double &Balance);
void overdraftMenu(double &Balance);
void viewBalance(double &Balance);
void BuisnessOverdraft(double &Balance);
void OverFiveOverdraft(double &Balance);
void UnderFiveOverdraft(double &Balance);


int main()
{   
    double Balance;
    pin(Balance);
    return 0;
}

void pin(double &Balance)
{
    int AccountPin = 8376;
    int AttemptNum = 0;
    int Pin;

    do
    {
        cout << "Enter your pin: ";
        cin >> Pin;
        if (Pin == AccountPin)
        {
            menu(Balance);
        } 
        else
        {
            cout << "Wrong pin, please try again." << endl;
            AttemptNum++;
        }
    } while (AttemptNum < 3);
    cout << "You have used all of your attempts, you can no longer attempt with this card" << endl;
    return;
}

void menu(double &Balance)
{
    int choice;

    do {
        cout << "Please choose from these options:\n1: Withdraw\n2: Deposit\n3: View balance\n4: Apply for an Overdraft\n5: Help menu\n6: Exit\nPlease choose between 1 and 6: ";
        cin >> choice;

        switch (choice)
        {
        case 1:
            withdraw(Balance);
            break;
        case 2:
            deposit(Balance);
            break;
        case 3:
            viewBalance(Balance);
            break;
        case 4:
            overdraftMenu(Balance);
            break;
        case 5:
            helpMenu();
            break;
        case 6:
            exit(EXIT_FAILURE);
            break;
        default:
            cout << "Please try again" << endl;
            break;
        }
    } while (choice < 0 || choice > 6);
}

void helpMenu()
{
    cout << endl << "When prompted by the interface please input a number between the numbers it says.\nYou cannot withdraw more than £200\nIf you have nothing left in your account you can apply for a overdraft" << endl << endl;
    return;
}

void withdraw(double &Balance)
{   
    double withdraw;
    cout << "How much would you like to withdraw: ";
    cin >> withdraw;
    menu(Balance);
    Balance = Balance - withdraw;
    if (Balance < 0) {
        cout << "You need to apply for an overdraft" << endl;
        Balance =- withdraw;
    }
    return;
}

void deposit(double &Balance)
{
    double deposit;
    cout << "How much you like to deposit: ";
    cin >> deposit;
    menu(Balance);
    Balance =+ deposit;
    return;
}

void viewBalance(double &Balance)
{
    menu(Balance);
    double balance = Balance;
    cout << "You have " << char(156) << balance <<  " in your bank account" << endl;
    return;
}
void overdraftMenu(double &Balance)
{
    char choice;
    do {
        cout << "Would you like to apply for a overdraft, yes or no? ";
        cin >> choice;
        tolower(choice);
        if (choice == 'y') {
            overdraft(Balance);
        }
        else if (choice == 'n') {
            return;
        }
        else cout << "Please try again";
    } while (choice != 'y' || choice != 'n');
}

void overdraft(double &Balance)
{
    int choice;
    do {
        cout << "Are you:\n1: A buisness owner\n2: A customer of over 5 years\n3: A customer of under 5 years\nPlease enter a number between 1 and 3";
        cin >> choice;
        switch (choice)
        {
        case 1:
            BuisnessOverdraft(Balance);
            break;
        case 2:
            OverFiveOverdraft(Balance);
            break;
        case 3:
            UnderFiveOverdraft(Balance);
            break;

        default:
            cout << "Input a correct value\nPlease try again";
            break;
        }
    } while (choice < 1 || choice > 3);
}


void BuisnessOverdraft(double &Balance)
{
}

void OverFiveOverdraft(double &Balance)
{
}

void UnderFiveOverdraft(double &Balance)
{
}

我正在为学校工作创建一个ATM程序，我需要使用参数传递来获得余额值，存款，取款和申请透支。但是当我运行代码然后存入余额不会增加。我还需要添加一个系统来保存用户详细信息，例如名称和帐户详细信息，这需要保存到文本文件中。

Answer 1

问题是，您将Balance定义为局部变量。这意味着它在函数体外无效=＆gt;它被摧毁了。

最简单的解决方案 - 如果可以接受，并且如果我正确理解您的问题 - 是您将其设为全局（当然还要删除本地定义）。

全球不可能：

然后你需要通过引用将Balance传递给每个func。功能定义的第一个例子：

void pin(double& Balance){ .... }

称之为：

int main()
{
   double Balance;
   ...
   pin(Balance);
   ...
}

从您调用菜单的pin，所以您必须对菜单（）执行相同的操作：

void menu(double& Balance) { ... }

并以相同的方式修改您从菜单中调用的每个功能。

下一步删除

的所有本地定义

double Balance;

!! BUT !! - 只在main（）

中保留

Answer 2

您的代码中存在几个主要缺陷：

你不应该在每个函数的末尾调用menu() - 这会导致递归。只需return来自函数，do while循环将继续迭代。
menu中的循环条件错误。您可以在while(true)上执行return和case 6，也可以while (choice != 6)。您不需要在那里exit(EXIT_FAILURE)。这样，它会将控制权返回给main并正确退出程序。
不要在函数中本地声明Balance。只声明一次（menu看起来像个好地方）并将其作为对需要它的每个函数的引用传递。

Answer 3

你需要在这里进行一些修正。首先，您使用的是函数本地的局部变量，一旦控制从函数返回，该局部变量值将不再可用。首先要了解全局变量和局部变量。你应该使用像

这样的结构

          customer{
                      char customerName[200];
                  double balance = 0;
                  };

如果你不了解结构声明并使用它，最好先学习它。

我只是修改你的代码以暂时修复它。

 double Balance = 1000.00; 
 int main()
 {
 }
 //declare Balance as global variable just above your main function.

 //modify your balance method like below
 void balance(double & balance)
 {
    balance = Balance;
 }

void deposit()
{
    double deposit;
    //double balance;//this is your local variable
    cout << "How much you like to deposit: ";
    cin >> deposit;
    //balance(balance);
    //Balance = balance + deposit; 
    //here in above Balance is your global variable   
    //better use a setBalance() method like below
    setBalance(deposit);
    menu();
}

void setBalance(double deposit)
{
    Balance = Balance + balance;
}
//This is your new method

这将解决您的问题。但它仍然没有达到标准。关于在文件中存储值，只需学习如何用C ++或C创建和读/写文件。首先自己尝试。如果您遇到任何麻烦，我们可以帮助您。

好运！

错误：如何通过参数传递解决此问题？

3 个答案: