Question

Random accesses to a file. A file contains a formatted list of 9999 integers that are randomly generated in the range of [1,9999]. Each integer occupies one single line and takes 4 characters' space per line. Alternatively, you can think that each number takes 5 characters' space, four for the number and one for the newline character. Write a C++ program using the seekg() and seekp() functions to insert the numbers 7777 through 7781 between the 6000-th and 6001-st numbers of the input file. Below are a few useful tips:

The tellg() and tellp() functions return the position of the current character in an input stream or output stream, respectively.

You are strongly recommended to use the tellg() function to first learn about the starting position of each integer. This will help you locate the exact starting position to insert the new numbers.

You can use the width() function to specify the number of characters you'd like an integer to occupy.

In addition to the "output" operator (<<), you can also use the write() function to write to a file.

Before you insert the numbers, you will need to first store all the numbers from the 6001-st number in an internal data structure, e.g., array. Otherwise, some of them will be overwritten.

Finally, always call the clear() function before calling the seekg() or seekp() function. Otherwise, you might encounter inexplicable behaviors.

Requirements:

You are not allowed to create or use any other files except the single input file.

You must use seekg() or seekp() to directly identify the insertion point to insert the new numbers.

It's acceptable to hardcode the input file name and implement everything in the main() function. However, it's preferred to create a separate function that handles the insertion of new numbers.

Answer 1

#include <iostream>

#include <fstream>

#include <vector>

#include <iomanip>

using namespace std;

int main()

{

         <int> numberVector;

               int createArray[10000]; /*array of 10000 numbers */

               const int SKIP_NUMBER = 6000;//This is the number in file to skip to

               int numberofBytes = 5;//This is the number of bytes to be read in(4byte num + newline)

               int productnew = (numberofBytes * SKIP_NUMBER);// This is meant to be used with seekg()

               fstream file("numbers.txt");

               if (!file)

               {

                               cout << "This file cannot be opened\n";

                               exit(1); //exit program

               }

               //cout << "check";

               /*file.seekg(productnew);//This will helps us to skip to the pointer to start adding new nums

               while (file.is_open())//Thia is to read in the numbers of the file

               {

                               int nextNumber;

                               file >> nextNumber;

                               if (file.fail())

                               {

                                              break;

                               }

                               numberVector.push_back(nextNumber);// The given subscript is out of range  here

               }

.

               file.clear();//This will clear the file handles

               file.seekp(productnew);

               for (int i = 7777; i <= 7781; i++) //This will help us to insert 5 new numbers starting at pos. 6001

               {

                               file << i << endl;

               }

               for (int i = 6006; i <= 9999; i++) //            This will help us to continue to add the rest of the numbers from the file

               {

                               file << numberVector[i] << endl;

               }

               int countnum = 0;

               while (!file.fail())

               {

                               int number;

                               file >> number;

                               if (number == SKIP_NUMBER)

                               {

                                              break;

                               }

               }

               int numLoc = file.tellg();

               //cout << "To check ";

               file >> createArray[countnum];//The subscript is out of range

               //cout << "to check once";

               while(!file.fail())

               {

                               count++;

                               file >> createArray[countnum];

               }

               //cout << "to check twice";

               file.clear();

               file.seekp(productnew);

               for (int i = 7777; i <= 7781; i++)

               {

                               file << i << endl;

               }

               //cout << "check thrice";

               for (int i = 0; i < count; i++)

               {

                               file << createArray[i] << endl;

               }

               //cout << "final check";

               cout << "The numbers are getting placed in a proper order";

               file.close();

               return 0;

}