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I have the following code and it works pretty good (other than the fact that it's pretty slow, but I don't care much about that). It doesn't seem intuitive that this would write the entire contents of the infile to the outfile.
// Returns 1 if failed and 0 if successful
int WriteFileContentsToNewFile(string inFilename, string outFilename)
ifstream infile(inFilename.c_str(), ios::binary);
ofstream outfile(outFilename.c_str(), ios::binary);
if( infile.is_open() && outfile.is_open() && infile.good() && outfile.good() )
outfile << infile.rdbuf();
outfile.close();
infile.close();
return 1;
return 0;
Any insight?
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iostream
classes are just wrappers around I/O buffers. The iostream
itself doesn't do a whole lot… mainly, it the provides operator>>
formatting operators. The buffer is provided by an object derived from basic_streambuf
, which you can get and set using rdbuf()
.
basic_streambuf
is an abstract base with a number of virtual functions which are overridden to provide a uniform interface for reading/writing files, strings, etc. The function basic_ostream<…>::operator<<( basic_streambuf<…> )
is defined to keep reading through the buffer until the underlying data source is exhausted.
iostream
is a terrible mess, though.
Yes, it's specified in the standard and it's actually quite simple. rdbuf()
just returns a pointer to the underlying basic_streambuf
object for the given [io]stream
object.
basic_ostream<...>
has an overload for operator<<
for a pointer to basic_streambuf<...>
which writes out the contents of the basic_streambuf<...>
.
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