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If I run the following code, no file is created at all:
std::ofstream outputFile(strOutputLocation.c_str(), std::ios::binary);
outputFile.write((const char*)lpResLock, dwSizeRes);
outputFile.close();
However, if I add a flush() before the close, it works:
std::ofstream outputFile(strOutputLocation.c_str(), std::ios::binary);
outputFile.write((const char*)lpResLock, dwSizeRes);
outputFile.flush();
outputFile.close();
Does the standard library actually require this, or is it a bug in the Visual C++ CRT?
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In oder to force all buffered writes to take place immediately, you can flush the stream. You can do this either directly by invoking the flush() method or through the std::flush stream manipulator: std::ofstream os("foo. txt"); os << "Hello World!" << std::flush; char data[3] = "Foo"; os.
std::exit() destroys objects with static storage duration (thereby flushing such ofstream objects). It does not destroy objects with automatic storage duration (leaving such ofstream objects unflushed).
This article focuses on closing the file. In a case, if a C++ program terminates, then it automatically flushes out all the streams, releases all the allocated memory, and closes all the opened files.
Note that any open file is automatically closed when the ofstream object is destroyed.
It's a bug. Reading §27.8.1.10/4, abridged:
void close();
Effects: Callsrdbuf()->close()...
What does rdbuf()->close() do? According to §27.8.1.3/6, abridged, emphasis mine:
basic_filebuf<charT,traits>* close();
Ifis_open() == false, returns a null pointer. If a put area exists, callsoverflow(EOF)to flush characters. ...
That is, it's suppose to flush. (Indeed, the call to flush() ultimately does the same thing.)
Note the call to close() itself isn't needed, as the destructor of basic_ofstream will call close().
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