Question

下面是我正在编写的代码，用于了解如何在C ++中使用文件。我有正确读取和写入的所有内容，但我无法让我的显示器显示正确的值，因为当我尝试初始化while循环中的Total变量时它忽略了。

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

int main()
{
    int customerNumber;
    double beginningBalance, purchase, payments, financeCharge, endingBalance;
    double beginningTotal, purchaseTotal, paymentsTotal, financeChargeTotal, endingTotal;
    ifstream inputFile;
    ofstream outputFile;

    inputFile.open("BeginningBalance.dat");
    outputFile.open("EndingBalance.dat");
    cout<<"Cust No | Beginning Bal | Finance Charge | Purchases | Payments | Ending Balance"<<endl;

    while (inputFile >> customerNumber)
    {
        outputFile <<customerNumber<<endl;
        inputFile >> beginningBalance;
        inputFile >> purchase;
        inputFile >> payments;

        financeCharge = beginningBalance * .01;
        endingBlanance= beginningBalance + purchase + financeCharge - payments;

        //***********************************************
        //This is where I am having trouble initializing variables.
        //***********************************************
        beginningTotal += beginningBalance; //beginningTotal not being intitialized.
        financeChargeTotal += financeCharge;
        purchaseTotal += purchase;
        paymentsTotal += payments;
        endingTotal += endingBalance;

        outputFile <<fixed<<setprecision(2)<<endingBalance<<endl;

        cout<<setw(5)<<customerNumber<<fixed<<setprecision(2)<<"        "<<beginningBalance<<"        "<<financeCharge<<"          "<<purchase<<"       "<<payments<<"       "<<endingBalance<<endl;
    }
    cout<<"Total:    "<<fixed<<setprecesion(2)<<beginningTotal<<"   "<<financeChargeTotal;
    system ("PAUSE");
    return 0;
}

Answer 1

您没有首先初始化变量，因此它们没有任何初始值。然后你向这些变量添加一些东西，结果是未定义的（读取垃圾）。

考虑将它们声明为：

double beginningTotal = 0, purchaseTotal = 0, paymentsTotal = 0, financeChargeTotal = 0, endingTotal = 0;

......甚至更好 - 为他们创造一些结构。

Answer 2

beginningTotal += beginningBalance

与

意思相同

beginningTotal = beginningTotal + beginningBalance

在循环之前没有初始化beginTotal，所以第一次得到

beginningTotal = _indeterminant_value_ + beginningBalance

因此，BeginTotal始终是一个不确定的值。通过不使用未初始化的变量来修复它。

double beginningTotal = 0.0;

无法初始化变量

2 个答案: