Question

I have a program in C++ which accepts some text from the user and saves it to a text file. Here are snippets of the program:

#include "stdafx.h"
#include <ctime>
#include <fcntl.h>
#include <iostream>
#include <string>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>
#include <Windows.h>

using namespace std;

int file_descriptor;
size_t nob;

int check_file(const char* full_path) //Method to check whether a file already exists
{
    file_descriptor = open(full_path, O_CREAT | O_RDWR, 0777); //Checking whether the file exists and saving its properties into a file descriptor
}

void write_to_file(const char* text) //Method to create a file and write the text to it
{
    time_t current = time(0); //Getting the current date and time
    char *datetime = ctime(&current); //Converting the date and time to string

    nob = write(file_descriptor, "----Session----\n\n"); //Writing text to the file through file descriptors
    nob = write(file_descriptor, "Date/Time: %s\n\n", datetime); //Writing text to the file through file descriptors
    nob = write(file_descriptor, "Text: %s", text); //Writing text to the file through file descriptors
    nob = write(file_descriptor, "\n\n\n\n"); //Writing text to the file through file descriptors
}

There are three main problems with this program:

1. Visual Studio is telling me that it cannot open source file <unistd.h> (no such file or directory).

2. Identifier open is undefined.

3. Identifier write is undefined.

How can I solve these problems please? I am using Visual Studio 2010 on a Windows 7 platform. I would like to make use of file descriptors in my program.

Answer 1

open and write are (Unix) platform specific. The C standard way for file access is FILE*, fopen and fwrite.

If you stil want to use open/write you should take a look at http://msdn.microsoft.com/en-us/library/z0kc8e3z(v=vs.100).aspx. Microsoft has added support for open/write, but renamed the (non-C-standard) functions to _open/_write.