makefile.cpp

#include <iostream>
#include <pthread.h>
#include <unistd.h>
#include <algorithm>
#include <chrono>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <exception>
#include <fstream>
#include <string>
#include <thread>
#include <vector>
#include <ctime>
#include<sys/shm.h>
#include <sys/ipc.h>

using namespace std;

int main()
{
   
    //take input from the user
    string filename;
    cout << "Enter the name of the file to be created: ";
    cin >> filename;

    fstream file;
    file.open(filename.c_str(), ios::out);


    if (!file)
    {
        cout << "Error in creating file!!!";
    }
    else
    {
        std::string str;
        int choice;
        std::cin.ignore();
        std::cout << "\nBegin from here.....\n";
        getline(std::cin,str);
        file << str;
        file.close();
        std::cout << "\nDo you want to save file?\n";
        std::cout <<"1.YES  2.NO\n";
        std::cin >> choice;
        if (choice == 1)
        {
            int file_size = 200; 
            int shm_id;
            key_t key = ftok(".", 'R');
            shm_id = shmget(key, 1024, IPC_CREAT | 0666);
            if (shm_id == -1)
            {
                std::cerr << "Failed to create shared memory.\n";
                return 1;
            }
            int *shared_memory = ( int *)shmat(shm_id, NULL, 0);
            if (shared_memory == ( int*)-1)
            {
                std::cerr << "Failed to attach shared memory.\n";
                return 1;
            }
            
 *shared_memory = *shared_memory * 1024;// converting gb to kb
if (file_size < *shared_memory)
{
    *shared_memory = *shared_memory- file_size;
     cin.get();
    std::cout << "File created successfully!\n";
    
    shmdt(shared_memory);
    shmctl(shm_id, IPC_RMID, NULL);
}
else
{
    file.open(filename.c_str()); //to format the file
    file.close();
    std::cerr << " NOT ENOUGH SPACE \n";
    return 1;
}
  shmdt(shared_memory);
}
else if (choice == 2)
        {
           
            std::cerr<<"closed without saving!\n";
        }
    }

   
    //wait for the user to press key to terminate program
    std::cin.get();
    return 0;
}