Can you have an ifstream and ofstream open for one file at once?

This is my first post, so please go easy on me ;).

I intend to both read from and write to a file. Can I have an ifstream and ofstream open for the same file at the same time? Or do I have to close one before I open the other?

Also, will the following code work to ensure the file I am writing to does not already exist, thus preventing overwriting?

Code:

---


    ofstream target_out; // ofstream to write to target file
    bool done = false;
    char targetname[80];

    while( !done ) {
        cout << "Enter data target file: ";
        cin >> targetname;
        target_out.open( targetname, ios::nocreate );

        if( target_out.is_open() ) {
            cout << "The file you entered already exists." << endl;
            target_out.close();
        }
        else
            done = true;

    }

    target_out.open( targetname, ios::noreplace );

---

Thanks!

Code:

---

fstream file; //fstream object
file.open("myfile.txt", ios::in|ios:: out); //open for input and output

---

Hope that helps. :)

Great, that helps a lot. My only question then is how do I ensure that I am not opening a pre-existing file for output; in other words, I wish to prevent any sort of overwriting. Thanks again!

Code:

---

fstream file; //fstream object
file.open("myfile.txt", ios::in|ios:: out|ios:: app); /*open for input and output Appending to file only*/

---

I believe that's it.

Sorry, what I meant was basically "do not open the file if it already exists." I don't want to be able to write to a file if it already exists.

Well try replacing ios:: app with ios:: nocreate

Allright, forget that, I can't read today, probably need to use an if statement like so:

Code:

---


if(!(file.open("myfile.txt", ios:: in|ios:: out|ios::nocreate))){
            // do reading and writing
}
else{
            cout<<"File aready exists";
}

---

wouldnt it be more like this:

Code:

---

if(file.open("file.txt"), ios::in  | ios::out | ios::nocreate)
{
    cout << "File already exists";
} else {
    // do reading and writing
}

---

[EDIT]Stupid Smilies[/EDIT]

If you look again you'll see the '!' operator(not), essentially both are codes evaluate the same. I hate those smilies too.

oooo sorry :D didnt see the ! there

[EDIT]Sureee smilies dont apear when i want them to[/EDIT]