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c++cfstreamcrt

fstream file I/O question - when to close a file stream

I am trying to work out if I need to call close on a fstream object if the intial open failed.

i.e.

std::fstream strm;
strm.open( "filename" );

if( ! strm.fail() )
{
    // Do something

    strm.close();  // [1]
}

strm.close();  // [2]

Where should close be called here - should it always be called [2] or only if the open succeeds[1]?

I may be going over the top here, but coming from the Windows API way of typically doing this I have CloseHandle( ... ); embedded in my mind :-)

Solution

  • The stream will be automatically closed by the fstream's destructor - there is no need to close it explicitly, unless your program logic demands it, for example if you are going to re-open it. However, closing a stream that didn't open won't cause any problems.