FStream I/O / Dynamically allocated arrays triggering breakpoint

Question

Basically, the point of this function is to take a set of student data and sort it by the student's ID number and print it out to a new file. The breakpoint seems to be occurring in the loop that writes to the output file but I am not sure because it seems like all cout statements I make after still are read to the console.

void file_score(char* infile, char* outfile)
{
    int size;

    ifstream fin(infile);

    fin >> size;
    
    int *student_id = new int(size);
    char *grade = new char(size);
    double *gpa = new double(size);
    //Creates new arrays of size that is read from file.

    for (int i = 0; i < size; i++)
    {
        fin >> student_id[i] >> grade[i] >> gpa[i];
        int temp_id = student_id[i];
        char temp_grade = grade[i];
        double temp_gpa = gpa[i];


        int j;
        for (j = (i - 1); j >= 0; j--)
        {
            if (student_id[j] < temp_id) {
                break;
            }
            student_id[j + 1] = student_id[j];
            grade[j + 1] = grade[j];
            gpa[j + 1] = gpa[j];
        }

        student_id[j + 1] = temp_id;
        grade[j + 1] = temp_grade;
        gpa[j + 1] = temp_gpa;
        //Using insertion sort to sort data as its being scanned in.    
    }

    fin.close();

    ofstream fout(outfile);
    for (int k = 0; k < size; k++)
    {
        fout << student_id[k] << " " << grade[k] << " " << gpa[k] << "\n";
    }
    //Print to file

    fout.close();
    delete []student_id;
    delete []grade;
    delete []gpa;
}

Answer 1

These statements are wrong:

int *student_id = new int(size);
char *grade = new char(size);
double *gpa = new double(size);

You are not allocating 3 arrays , you are actually allocating 3 single values . So, when your loops are trying to access the array elements afterwards, they are accessing memory incorrectly, causing undefined behavior that is likely corrupting memory.

Change those statements to this instead:

int *student_id = new int[size];
char *grade = new char[size];
double *gpa = new double[size];

A better solution is to use std::vector instead of new[] directly, though:

std::vector<int> student_id(size);
std::vector<char> grade(size);
std:vector<double> gpa(size);