gistfile1.c

#include <iostream>
#include <fstream>
#include <string>
#include <windows.h>

using namespace std;

bool openInFile (ifstream &, char []);
bool openOutFile (ofstream &, char []);

struct student
{
    char name[25];
    int exam[3];

};
student bclass;

int main()
{
    char bfr;                                                   //Since we are reading from binary file, we are reading byte by byte, byte goes from 0x00 to 0xFF hence our buffer that we will use must be right type
                                                                // !!!! You can't use integer, cause int's have 4 bytes, and when u write one byte to it (remember we r reading bytes, and points from every exam are represented by 1 byte) u will only fill first byte
                                                                //And cause of that rest 3 bytes will have some random values that were assigned to them when our variable was declared !!!!
    int firstNameLength = 0;
    int lastNameLength = 0;

    ifstream input;
    openInFile (input, "quizzes.dat");

    ofstream output;
    openOutFile (output, "quizzes.txt");

    output << "=================================================\n";

    for(int i = 0; i < 5; i++)
    {

        input.ignore(25, 0x20);                                 //Ignoring first 25 chars or ignoring x chars until we bump onto ' ' (if u open .dat file with some hexeditor u will see that space is representet by 0x20 hexadecimal)
        firstNameLength = input.gcount();                       //firstNameLength = number of chars that we passed until we found ' '

        input.ignore(25, 0x20);                                 //Ignoring next 25 chars or ignoring x chars until we bump onto ' '
        lastNameLength = firstNameLength + input.gcount();      //lastNameLength = firstNameLength + number of chars we passed until we found another ' ', lastNameLength now holds value that is length of our name and lastname together

        if(i == 4)                                              //Milhouse have middle name included so we must do this once again in his case so we don't skip his lastname
        {
            input.ignore(24, ' ');
            lastNameLength += input.gcount();
        }

        for(int i = 0; i < lastNameLength; i++)
        {
            input.unget();                                      //Decrease the current location in the stream by one character, and repeting so until we get to the first char of the first name
        }

        input.readsome((char*)&bclass.name, lastNameLength);    //Since we moved current location in the stream to the first char of the first name we are taking lastNameLength chars and putting them in bclass.name

        for(int i = 0; i < 3; i++)                              //Until we find all 3 right values, we have 3 exams right?
        {
            input.read((char*)&bfr, 1);                         //Read one char from stream

            if(bfr != 0x20)                                     //If char that we read is not ' ' (0x20 hex) than it's some value that probably represents number of points of particular exam, thats what we are looking for
            {
                bclass.exam[i] = (int)bfr;                      //We take that char, cast it to int since our bclass.exam is type int, and store it in corresponding exam
                input.get();                                    //Than we increase the curret location in the stream by one
            }else                                               //else, if char that we found is space, we just skip it and reapeat
            {
                input.get();
            }

        }

        output << bclass.name << " " << bclass.exam[0] << " " << bclass.exam[1] << " " << bclass.exam[2] << endl;
    }

    output << "=================================================\n";

    input.close();
    output.close();

    system("pause");

    return 0;
}

// Opens and checks input file
bool openInFile (ifstream &in, char filename[])
{
    in.open(filename, ios::in | ios::binary);

    if (in.fail())
    {
        cout << "ERROR: Cannot open quizzes.dat\n";
        //exit(0);
    }
    return in.fail();
}

// Opens and checks output file
bool openOutFile (ofstream &out, char filename[])
{
    out.open(filename, ios::out);

    if (out.fail())
    {
        cout << "ERROR: Cannot open quizzes.txt\n";
        //exit(0);
    }
    return out.fail();
}