how to open ofstream in exclusive mode

using ofstream, how can I open a file in exclusive mode? Someone told me that was the default, but in my test using VC++ 6.0 on XP that's not the case. I wrote a simple console program (see below) and all instances was able to successfully open and write to the file.

Code:

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


int main(int argc, char* argv[])
{
        ofstream out("hello.txt",ios::app);
        if(out.is_open())
        {
                cout << "File is open.. press <Enter> to continue ...";
                out << "Hello World" << endl;
                cin.get();
                out.close();
        }
        else
        {
                cout << "File failed to open.. press <Enter> to continue ...";
                cin.get();
        }
        return 0;
}

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I don't really know myself, but in giving it a quick search, I found this link talking about using <fctrl.h> for that:

C++ Reference Guide

Quote:

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Although it may not be everyone's cup of tea, C's original I/O library (to which, henceforth, I will refer as <fcntl.h>) is still alive and kicking...
... Yet, unofficially, this library is supported on every major platform. One of its major advantages over <fstream> is its tighter control over file I/O operations. For instance, you can use flags that open a file in exclusive mode, or open a file only if it already exists...

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Again, I don't know if this helps, but you could check it out if you wish.

Aside from that, I also found these arguements to pass the open() command in <fstream>:

Protection
The protection mode of the file
filebuf::sh_compat
Compatibility share mode (MS-DOS only).
filebuf::sh_none
Exclusive mode no sharing.
filebuf::sh_read
Read sharing allowed.
filebuf::sh_write
Write sharing allowed.

This may be more what you want. For reference, it's from here.

unfortunately filebuf::sh_none is only defined in <fstream.h> and not in <fstream>. I agree with your quote that C's file i/o is a lot superior to c++ fstream class. I suppose my only option is to use fsopen() where I can specify the sharing mode. Stupid c++ :mad:

Quote:

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The third argument protection is
used as the file permissions. It does not appear in the Standard C++
description and is provided as an extension. It determines the file
read/write/execute permissions under UNIX. It is more limited under
DOS since files are always readable and do not have special execute
permission.

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nmnmnm

7stud: MS-Windows function _fsopen() allows and enforces opening a file in exclusive mode (see example below). I'm not running MS-DOS, but XP (which has NO MS-DOS code in it)
So why doesn't fstream??? (answer: c++ fstream is a crappy horrible class.)

Code:

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#include <stdio.h>
#include <share.h>

int main() /* program main begins execution */
{
        FILE* fp = _fsopen("myfile.txt","a",_SH_DENYRW);
        if(fp != NULL)
        {
                fprintf(fp,"Hello World\n");
                printf("File opened ok -- press <Enter>");
                getchar();
                fclose(fp);
        }
        else
        {
                printf("File open failed --press <Enter>");
        }


  return 0;  /* indicates successful program execution */
}

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