当我尝试输入＆＃34; x＆＃34;时，为什么会出现分段错误？退出我的程序

Question

  

当我输入“x”退出程序时，DataDisplayAndSearch函数由于某种原因导致分段错误。我试过调试，无法弄清问题是什么。这是家庭作业

string DataDisplayAndSearch (int customerCount, string ssn[])
{
    //local variables
    int index;
    int count;
    int numberLen;
    int numberLocation = NOT_FOUND;
    int high;
    int low;
    int middle;
    bool invalidNumber = false;
    string choice;

    cout << " Social Security Numbers on file are:" << endl;

    for (index = 0; index < customerCount; index++)
    {
        cout << " " << ssn[index] << " ";
    }
    do
    {
        cout << endl << endl << " Enter SSN to find (or X to exit):";
        invalidNumber = false;
        cin >> choice;

        if (choice != EXIT && choice != EXIT1)
        {
            numberLen = choice.length();

            if (numberLen < LENGTH || numberLen > LENGTH) 
            {
                invalidNumber = true;
            }

            for (count = 0; count < LENGTH; count++)
            {
                if (isprint(choice[count]));
                else
                {
                    invalidNumber = true;
                }
            }

            if (choice[IDX2] != DASH || choice[IDX5] != DASH)
            {
                invalidNumber = true;
            }

            low = 0;
            high = customerCount - 1;

            while ((low <= high) && (numberLocation == NOT_FOUND))
            {
                middle = (low + high) / 2;

                if (choice > ssn[middle])
                {
                    high = middle - 1;
                }
                else if (choice < ssn[middle])
                {
                    low = middle + 1;
                }
                else
                {
                    numberLocation = middle;
                }
            }

            if (numberLocation == NOT_FOUND)
            {
                cout << " Error!! Please enter a valid SSN." << endl;
            }

            if (invalidNumber)
            {
                cout << " Input dashes and digits " << choice << " are formatted."
                     << " SSN must be exactly 11 characters long, formatted as:"
                     << " ###-##-###" << endl;
            }

        } //end of if

    } while (((invalidNumber) && (choice != EXIT && choice != EXIT1 ) && (numberLocation == NOT_FOUND)));
}

Answer 1

当外环出于任何原因退出时，包括choice == EXIT，函数退出时不提供类型string的返回值。然后调用者尝试使用不存在的string对象，因此崩溃。

使用非void返回类型越过函数的右大括号是未定义的行为。它可能会崩溃，但每次都不会崩溃。如果您可以在命令行上启用其警告功能，例如-Wall，则编译器可能会警告您这类事情。