howto open a file for writing several times

This is a discussion on howto open a file for writing several times within the C++ Programming forums, part of the General Programming Boards category; Hi, I would like to open a file for writing several times. I used append which works, but every time ...

  1. #1
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    howto open a file for writing several times

    Hi,
    I would like to open a file for writing several times. I used append which works, but every time I re-run the program the file grows. What I really want to do is only append after the first time the function has been called. So I tried doing like this.
    Code:
    	ofstream voxel;
    	if (nphases == 0) {
    		ofstream voxel (outname.c_str(), ios::out|ios::binary);
    	}
    	else {
    		ofstream voxel (outname.c_str(), ios::out|ios::binary|ios::app);
    	}
    Where nphases is growing every time the function is called in a loop so I know if it is the first time or not. However this didnt work. I hope I explain myself well enough =) Anybody know a good way to do this?

  2. #2
    Kiss the monkey. CodeMonkey's Avatar
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    I'm not sure what it is that you're doing. For one thing, every 'voxel' in that code snippet refers to a different object. What are you doing to the file in this function?
    "If you tell the truth, you don't have to remember anything"
    -Mark Twain

  3. #3
    Cat without Hat CornedBee's Avatar
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    Code:
    ofstream voxel;
    voxel.open(outname.c_str(), ios::binary | (nphases == 0 ? 0 : ios::app));
    (For all o*streams, ios::out is implicit.)
    All the buzzt!
    CornedBee

    "There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
    - Flon's Law

  4. #4
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    thanks

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