字符串下标超出了带有fstream的c++范围

我的代码：

#include <iomanip>
#include <iostream>
#include <string>
#include <cmath>
#include <cstdlib>
#include <fstream>
#include <ctime>
using namespace std;
void insertionSort(int arrtosort[], int size);
const int SIZE = 10;
int main() {
    ofstream out;
    ifstream ingrades;
    unsigned seed = time(0);
    char doAgain = ' ';
    int id = 0;
    string grade = " ";
    int choice = 0;
    int fileid[SIZE];
    int numgrade[SIZE];
    int sum = 0;
    int counter = 0;
    int average = 0;
    int idx = 0;
    string letterGrade = " ";
    srand(seed);
    out.open("dataout.txt");
    while(counter <= 10) {
        out << (10000 + rand() % 99999);
        out << " ";
        out << (-1 + rand() % 10) << endl;
        //out<<" ";
        counter++;
    }
    out.close();
    ingrades.open("dataout.txt");
    for(idx = 0; idx < SIZE; idx++ ) {
        ingrades >> fileid[idx] >> numgrade[idx];
        sum = sum + numgrade[idx];
        counter++;
    }
    ingrades.close();
    average = sum / counter;
    out.open("dataout.txt");
    for( idx = 0; idx < SIZE; idx++ ) {
        if(numgrade[idx] == average || numgrade[idx] == average + 1) {
            out << fileid[idx] << " " << numgrade[idx] << " B";
            out << endl;
        } else if(numgrade[idx] == average + 2 || numgrade[idx] == average + 3) {
            out << fileid[idx] << " " << numgrade[idx] << " A-";
            out << endl;
        } else if(numgrade[idx] == average + 4 || numgrade[idx] >= 7 || numgrade[idx] == 10) {
            out << fileid[idx] << " " << numgrade[idx] << " A";
            out << endl;
        } else if(numgrade[idx] == average - 1) {
            out << fileid[idx] << " " << numgrade[idx] << " C";
            out << endl;
        } else if(numgrade[idx] == average - 2) {
            out << fileid[idx] << " " << numgrade[idx] << " F";
            out << endl;
        } else if (numgrade[idx] == -1) {
            out << fileid[idx] << " " << numgrade[idx] << " N/A";
            out << endl;
        }
    }
    out.close();
    ingrades.open("dataout.txt");
    for(idx = 0; idx < SIZE; idx++ ) {
        ingrades >> fileid[idx] >> numgrade[idx];
    }
    ingrades.close();
    do {
        cout << "n" << right << setw(35) << "Teacher's Menu" << right << endl;
        cout << "---------------------------------------------------------" << endl;
        cout << "1) Sort the student list by id, and write it to your file" << endl;
        cout << "2) Search for a student by id and display the id," <<
             " numeric and letter grade ton   the console" << endl;
        cout << "3) Search for students with a particular letter grade and display the resultsn   to the console" << endl;
        cout << "4) Sort the student list by numeric grade and write it out to a file" << endl;
        cout << "5) Find the percentage of students for a particular letter grade" << endl;
        cout << "ntPlease enter which number option you wish to use: ";
        cin >> choice;
        ingrades.open("dataout.txt");
        switch(choice) {
        case 1:
            break;
        case 2:
            ingrades.clear();
            cout << "Enter in Student id: ";
            cin >> id;
            idx = 0;
            for ( idx = 0; idx <= SIZE; idx++ ) {
                ingrades >> fileid[idx] >> numgrade[idx] >> letterGrade[idx];
                if ( fileid[idx] == id && idx <= SIZE ) {
                    cout << fileid[idx] << " " << numgrade[idx] << " " << letterGrade[idx] << endl;
                    break;
                }
            }
            system("pause");
            break;
        case 3:
            /*  cout << "Enter in the Student letter grade: ";
                cin >> grade;
                for(idx = 0; idx < SIZE; idx++) {
                    if(grade == letterGrade[idx])
                        cout << fileid[idx] << " " << numgrade[idx] << " " << letterGrade[idx] << endl;
                }
                break;
                */
        case 4:
            break;
        case 5:
            break;
        default:
            cout << "Incorrect option" << endl;
        }
        cout << "Would you like to go back to the main menu y or n: " << endl;
        cin >> doAgain;
    } while(doAgain == 'y' || doAgain == 'Y');
    ingrades.close();
    //system("PAUSE");
    return EXIT_SUCCESS;
}
void insertionSort(int arrtosort[], int size) {
    int temp = arrtosort[0];
    for(int i = 1; i <= size; i++) {
        temp = arrtosort[i];
        int j = 0;
        for(j = i; j > 0; j--)
            if(temp < arrtosort[j - 1])
                arrtosort[j] = arrtosort[j - 1];
            else break;
        arrtosort[j] =  temp;
    }
}

这是一个学校的项目，但我没有通过课程，但我决心完成这个项目，继续学习。真的需要帮助。我觉得自己碰壁了。

我正试图从一个文本中读取ID，它也起作用，第四次我会出现错误。我想了解为什么这不起作用，以及我如何继续执行程序的其余部分。非常感谢任何和所有的帮助。也可以使用应用我的自动排序功能的帮助。老师给了我们循环，但不确定它是如何完全起作用的，也不确定如何正确应用它。

我遇到的麻烦从第127行开始，直到出现错误，比如字符串子字符串超出范围，以及在情况3 中比较字符串时遇到困难