Why my previous file delete???

my code is as below...
i wan add student in my txt file...
when i close system, restart again and add student... the previous data that i entered lost...WHY???

Code:

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int main()
{
    int ans, loop;
    for (loop=0; loop<3;loop++)
    {
    cout<<"Enter 1 to add student or 2 to view Student: ";
    cin>>ans;
    if (ans==1)
    {    fstream outFile;
    const int QUIT = 0;
    int idNum;
    string name;
    double gpa;
    outFile.open("file2.txt", ios::out | ios::binary);
    cout<<"ENTER Student ID number or "<< QUIT << " to quit ";
    cin>>idNum;
    while (idNum!=QUIT)
    {
        cout<<"Enter Name: ";
        cin>>name;
        cout<<"Enter GPA: ";
        cin>>gpa;
        Student aStudent(idNum, name, gpa);
        outFile.seekp((idNum -1) * sizeof(aStudent));
        outFile.write(reinterpret_cast<const char*>(&aStudent), sizeof (Student));
        cout<<"Enter student ID number or "<<QUIT<<" to quit ";
        cin>>idNum;
    }
    outFile.close();
    return 0;
    }

    else

    {
    Student aStudent;
    ifstream inFile;
    const int QUIT = 0;
    int idNum;
    inFile.open("file2.txt", ios::in | ios::binary);
    inFile.read(reinterpret_cast<char*>(&aStudent), sizeof(Student));
    cout<<"ENTER Student ID number to view or "<< QUIT << " to quit ";
    cin>>idNum;
    while (idNum!=QUIT)
    {
        inFile.seekg((idNum -1) * sizeof(aStudent));
        inFile.read(reinterpret_cast<char*>(&aStudent), sizeof (Student));
        cout<<"ID : "<<aStudent.stuId<<endl;
        cout<<"Name : "<<aStudent.name<<endl;
        cout<<"GPA : "<<aStudent.gpa<<endl;
        cout<<"Enter student ID number or "<<QUIT<<" to quit ";
        cin>>idNum;
    }
    inFile.close();
    return 0;}
    }

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PLEASE HELP.....

I haven't checked all your code, but have a look at the flags for ofstream::open, there should be one to append to your file instead of overwriting it.

You should also check the return values of your functions. Maybe your files couldn't be opened?

Quote:

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Originally Posted by nvoigt

I haven't checked all your code, but have a look at the flags for ofstream::open, there should be one to append to your file instead of overwriting it.

You should also check the return values of your functions. Maybe your files couldn't be opened?

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Where should i chose to append???
Cause i initially created 10000 space for student using this code

Code:

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//create 10000space.
int main()
{
    const int maxRoom = 10000;
    Student aStudent;
    ofstream outFile;
    outFile.open("file2.txt", ios::out | ios::binary);
    for (int x = 0; x < maxRoom ; x++)
        outFile.write(reinterpret_cast <const char*> (&aStudent), sizeof(Student));
    outFile.close();
    return 0;
}

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Quote:

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the previous data that i entered lost...WHY???

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Because this:

Code:

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outFile.open("file2.txt", ios::out | ios::binary);

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erases the file when you open it. To open the file for appending you need to add ios::app to your statement.

Jim