Question

我有一个if语句，每当我实现它时，它都会引发＆＃34;读取访问冲突＆＃34;异常，即使我的所有其他if语句看起来非常相似并且有效。其他一切都很完美，所以让我感到困惑的是为什么会发生这种情况。

if let userInfo = Auth.auth().currentUser {
            userInfo.reload(completion: { (error) in
                guard error == nil else {
                    debugPrint(error.debugDescription)
                    return
                }
            })
}

全功能

if (records[i].studentArray[j].id == records[i-1].studentArray[j].id) //these two
                records[i].retained++;

.h文件中的学生和学期课程

void readFile()
{
//Function reads the file and displays all results
int i = 0;
int j = 0;
int count;
Semester records[25]; //only holds up to 25 semesters
Student studentArray;
string semesterName;
ifstream roster;
roster.open ("records.txt");
if (roster.is_open())
{
    roster >> semesterName;
    while(!roster.eof())
    {

        roster >> count;
        records[i].semesterName = semesterName; 
        cout << semesterName;
        records[i].numStudents = count;
        records[i].studentArray = new Student[count];

        for (j = 0; j < count; j++)
        {
            roster >> records[i].studentArray[j];
            if (records[i].studentArray[j].year == "FY")
                records[i].fycount++;

            else if (records[i].studentArray[j].year == "SO")
                records[i].socount++;

            else if (records[i].studentArray[j].year == "JR")
                records[i].jrcount++;

            else if (records[i].studentArray[j].year == "SR")
                records[i].srcount++;

            if (records[i].studentArray[j].id == records[i-1].studentArray[j].id)
                records[i].retained++;
        }
        cout << endl;
        cout << "FY: " << records[i].fycount << endl;
        cout << "SO: " << records[i].socount << endl;
        cout << "JR: " << records[i].jrcount << endl;
        cout << "SR: " << records[i].srcount << endl;

        cout << "FY gain/loss: " << records[i].fycount - records[i - 1].fycount << endl;
        cout << "SO gain/loss: " << records[i].socount - records[i - 1].socount << endl;
        cout << "JR gain/loss: " << records[i].jrcount - records[i - 1].jrcount << endl;
        cout << "SR gain/loss: " << records[i].srcount - records[i - 1].srcount << endl;

        cout << "Percentage gained/lost: " << static_cast<double>(records[i].numStudents - records[i - 1].numStudents) / records[i - 1].numStudents * MULTIPLIER << "%" << endl;

        cout << "Number of students retained: " << records[i].retained << endl;

        cout << endl;

        delete[] records[i].studentArray;
        roster >> semesterName;
        i++;
    }

    roster.close();
}
else
    cout << "Error: File not found" << endl;
}

谢谢！

Answer 1

跟踪您的申请。您将看到i最初设置为0，因此-1位置在数组中无效。

if (records[i].studentArray[j].id == records[i-1].studentArray[j].id)

这是错误的来源。最好将其改为：

if (i > 0 && records[i].studentArray[j].id == records[i-1].studentArray[j].id)

希望这有帮助。

C ++：抛出异常：按阵列读取访问冲突

1 个答案: