c++ - EXC_BAD_ACCESS 重新运行程序时

Question

所以这是我在类里面为 CS 实验室编写的程序。它被修改，以便它可以从一个文本文件接收输入并输出到另一个文本文件。完成计算后，它会询问用户是否要重新运行程序，这只是 main 中的一个 while 循环。为什么程序重新运行时会出现此错误？

线程 1:EXC_BAD_ACCESS(代码=1，地址=0x7ffeb1d82bc8)

它出现在 getPints 函数的这一行:

bloodInFile >> a[i];

#include <iostream>
#include <string>
#include <iomanip>
#include <math.h>
#include <fstream>

using namespace std;

const int MAX_HOURS = 7;

void getPints(double a[], int h);
double getAverage(double a[], int h);
double getHigh(double a[], int h);
double getLow(double a[], int h);
void displayInfo(double a, double b, double c);

int main()
{
    string again = "yes";
    double pints[MAX_HOURS];
    double getHigh(double pints[], int MAX_HOURS);

    while (again == "yes")
    {
        getPints(pints, MAX_HOURS);
        getHigh(pints, MAX_HOURS);
        displayInfo(getAverage(pints, MAX_HOURS), getHigh(pints, MAX_HOURS), getLow(pints, MAX_HOURS));

        cout << "Do you want to run again (yes or no)? ";
        cin >> again;
    }

    return 0;
}

void getPints(double a[], int h)
{
    int i;
    ifstream bloodInFile;

    bloodInFile.open("bloodDrive.txt");

    if (!bloodInFile)
        cout << "Cannot open file." << endl;

    while (!bloodInFile.eof())
    {
        bloodInFile >> a[i];
        i++;
    }

    bloodInFile.close();
}

double getAverage(double a[], int h)
{
    int i;
    double totalPints = 0;
    double averagePints;

    for (i = 0; i <= h - 1; i++)
        totalPints = totalPints + a[i];
    averagePints = totalPints / i;

    return averagePints;
}

double getHigh(double a[], int h)
{
    int i;
    double highest = a[0];

    for (i = 1; i < h; i++)
    {
        if (a[i] > highest)
            highest = a[i];
    }

    return highest;
}

double getLow(double a[], int h)
{
    int i;
    double lowest = a[0];

    for (i = 1; i < h; i++)
    {
        if (a[i] < lowest)
            lowest = a[i];
    }

    return lowest;
}
void displayInfo(double a, double b, double c)
{
    ofstream bloodOutFile;

    bloodOutFile.open("bloodResults.txt");

    bloodOutFile << "Average pints: " << setprecision(1) << showpoint<< fixed << a << endl;
    bloodOutFile << "Highest pints: " << setprecision(1) << showpoint<< fixed << b << endl;
    bloodOutFile << "Lowest pints: " << setprecision(1) << showpoint<< fixed << c << endl;
}

Answer 1

在函数 getPints 中检查您是否超出数组 a 的范围，在此处添加检查

 while (!bloodInFile.eof())
 {
   if(i >= h)
       break;
   bloodInFile >> a[i];
   i++;
 }

因为如果你可以在 bloodDrive.txt 文件中有更多行 MAX_HOURS。我也没有看到你在某个地方初始化了 i 我认为它应该等于 0 (i=0)，所以你的函数应该看起来像这样

void getPints(double a[], int h)
{
    int i = 0;
    ifstream bloodInFile;

    bloodInFile.open("bloodDrive.txt");

    if (!bloodInFile)
        cout << "Cannot open file." << endl;

    while (!bloodInFile.eof())
    {
        if(i > h)
            break;
        bloodInFile >> a[i];
        i++;
    }

    bloodInFile.close();
}

附言正如@JonathanLeffler 所说(我 100% 同意他的观点)，当您不知道可能有多少输入时，最好使用动态数组(例如 vector)来解决此类问题。