Darn files!! lol

I'm using Visual C++ 6.0 and I got this program but it won't work.

Program:

Code:

---

#include <iostream>
#include <fstream>
using namespace std;

int main()
{
        fstream file;
       

        int x;
        int j=12;

//get from file
file.open("data.txt",ios::in);

file >> x;

file.close();

        //put into file
                file.open("data.txt",ios::out);

                file << j;

                file.close();
       

        cout << x << endl;
        cout << j << endl;

        return 0;
}

---

Inside the file i have one number but when i try to write a different number into the same file I get nothing. The original number is erase and i'm left with nothing. Any suggestion...
Thankx :D

ios::out will erase the content of the file if there's any
ios::app will seek to end-of-file before each write

Also ALWAYS check to make sure the file is open. I tested your code and when you tried to reopen the file for writing it wouldnt open, so ALWAYS add code to check if the file open successfully.

When i use the "ios::out" it erase the value within the file and nothing else. When i use the "ios::app" the number remain the same and no other value was added into the file. Any other ideas....
< I need to read and write to the same file>!!

Thankx ;)

For fstream if i remember correctly you can combine the parameters with a | so it can do both reading and writing to the file?

Code:

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file.open("data.txt",ios::in | ios::out);

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Yeah, I try that before and again after mentioning file.open("data.txt",ios::in| ios::out); and that didn't work either.Is there any other way??
Thanx :(

I am as puzzled as you are. I can get it to work if i only use one or the other but not both. You could define and ifstream for input and an ofstream for output that works.

Code:

---

ifstream file_in;
ofstream file_out;

file_in.open("data.txt",ios::in);


file_out.open("data.txt",ios::app);

---

Code:

---

#include <iostream>
#include <fstream>
using namespace std;

int main()
{
  fstream file;

  int x;
  int j=12;

  //  open for reading
  file.open("data.txt",ios::in);
  if (!file)
    cout << "could not open file" << endl;

  file >> x;

  file.close();
 
  // once stream object is disconnected,
  // no further access is allowed unless
  // is reset
  file.clear();   
 
  // open file for writing, append to end of file
  file.open("data.txt", ios::out | ios::app);
  if (!file)
    cout << "could not open file" << endl;

  file << j;

  file.close();       

  cout << x << endl;
  cout << j << endl;

  return 0;
}

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