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With std::fopen, will it return a null pointer if the file does not
exist? If so, how do I make it so that it will attempt to create a
file if it doesn't exist? Would moving to fstreams/filebufs address
these issues?

--
I am only a mirage.

The documentation (eg,
http://www.die.net/doc/linux/man/man3/fopen.3.html ) says that if you
open the file for write or append (in addition to read if you'd like)
the file will be created if it doesn't exist.

And std::fstream would be preferred in c++ anyway. stream
insertion/extraction operators (<< and >>) are safer and more
extendable and such than printf/scanf style functions.

kelvSYC wrote:
> With std::fopen, will it return a null pointer if the file does not
> exist?

It depends on the mode argument to fopen().

> If so, how do I make it so that it will attempt to create a
> file if it doesn't exist?

That depends on the mode argument to fopen(). Did you read up on that?
Your documentation should explain.




Brian

Default User wrote:
> kelvSYC wrote:
> > With std::fopen, will it return a null pointer if the file does not
> > exist?
>
> It depends on the mode argument to fopen().

It may also depend on platform-specific things, such as file
permissions. That is, a file may exist but the application not have
permission to open it. That's why the trick of trying to open a file
for reading is not always an adequate test for file existence.



Brian

kelvSYC <> wrote:

(Assuming std::fopen behaves more or less like fopen() from C

> With std::fopen, will it return a null pointer if the file does not
> exist?

fopen returns a null pointer if the attempt to open the file fails.
This can happen for various reasons; one of which, of course, is that
the file does not exist. However, if the mode is "w" or "a", the file
will be created if it does not exist; if you get a null pointer in one
of these modes, something else has presumably gone wrong.

> If so, how do I make it so that it will attempt to create a
> file if it doesn't exist?

If you're opening for read, you can use "a+" as the mode; this will
open the file for read and write and create the file if it does not
exist.

> Would moving to fstreams/filebufs address
> these issues?

Probably, but I'll leave the answer to knowledgeable types.

--
Christopher Benson-Manica | I *should* know what I'm talking about - if I
ataru(at)cyberspace.org | don't, I need to know. Flames welcome.