Does ofstream::open create the file if it doesn't already exist?

This is a discussion on Does ofstream::open create the file if it doesn't already exist? within the C++ Programming forums, part of the General Programming Boards category; Will ofstream: pen( filename ) create the file with filename if the said file does not already exist?...

  1. #1
    Programming Ninja In-T...
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    Question Does ofstream::open create the file if it doesn't already exist?

    Will ofstream:pen(filename) create the file with filename if the said file does not already exist?

  2. #2
    Registered User jeffcobb's Avatar
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    ofstream:pen(filename) will create the file if it does not exist. If it does exist, what it does after open WRT the file ptr is dictated by the additional ios::XXX flags you pass in like:

    Code:
    ofstream::open(filename, ios::app);
    will open it in append mode...

    open - C++ Reference

    Check out the link for the other permutations..
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    Thanks.
    I had actually already checked out that link before asking the question. I just asked it because it does not mention at that link whether it creates the file or not.

  4. #4
    and the hat of sweating
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    I just wish the C++ IO classes had something similar to the O_EXCL flag for open(). Otherwise it just opens the door to race conditions.
    "I am probably the laziest programmer on the planet, a fact with which anyone who has ever seen my code will agree." - esbo, 11/15/2008

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  5. #5
    Registered User jeffcobb's Avatar
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    Quote Originally Posted by cpjust View Post
    I just wish the C++ IO classes had something similar to the O_EXCL flag for open(). Otherwise it just opens the door to race conditions.
    Wow you are right; even though most of my work is C++ nowadays I never used ofstream with any kind of access modifiers. If I needed to manage access to a file handle I just used the lower level calls. That said it would not be that hard to make your own wrapper for it and supply the access modifiers yourself..
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