basic_ofstream Class
The latest version of this topic can be found at basic_ofstream Class.
Describes an object that controls insertion of elements and encoded objects into a stream buffer of class basic_filebuf< Elem, Tr>, with elements of type Elem, whose character traits are determined by the class Tr.
Syntax
template <class Elem, class Tr = char_traits<Elem>>
class basic_ofstream : public basic_ostream<Elem, Tr>
Parameters
Elem
The basic element of the file buffer.
Tr
The traits of the basic element of the file buffer (usually char_traits< Elem>).
Remarks
When the wchar_t specialization of basic_ofstream writes to the file, if the file is opened in text mode it will write a MBCS sequence. The internal representation will use a buffer of wchar_t characters.
The object stores an object of class basic_filebuf< Elem, Tr>.
Example
The following example shows how to create a basic_ofstream object and write text to it.
// basic_ofstream_class.cpp
// compile with: /EHsc
#include <fstream>
using namespace std;
int main(int argc, char **argv)
{
ofstream ofs("ofstream.txt");
if (!ofs.bad())
{
ofs << "Writing to a basic_ofstream object..." << endl;
ofs.close();
}
}
Constructors
| basic_ofstream | Creates an object of type basic_ofstream. |
Member Functions
| close | Closes a file. |
| is_open | Determines if a file is open. |
| open | Opens a file. |
| rdbuf | Returns the address of the stored stream buffer. |
| swap | Exchange the contents of this basic_ofstream for the contents of the provided basic_ofstream. |
Operators
| operator= | Assigns the content of this stream object. This is a move assignment involving an rvalue reference that does not leave a copy behind. |
Requirements
Header: <fstream>
Namespace: std
basic_ofstream::basic_ofstream
Creates an object of type basic_ofstream.
basic_ofstream();
explicit basic_ofstream(
const char* _Filename,
ios_base::openmode _Mode = ios_base::out,
int _Prot = (int)ios_base::_Openprot);
explicit basic_ofstream(
const wchar_t* _Filename,
ios_base::openmode _Mode = ios_base::out,
int _Prot = (int)ios_base::_Openprot);
basic_ofstream(
basic_ofstream&& right);
Parameters
_Filename
The name of the file to open.
_Mode
One of the enumerations in ios_base::openmode.
_Prot
The default file opening protection, equivalent to the shflag parameter in _fsopen, _wfsopen.
right
The rvalue reference to the basic_ofstream object being used to initialize this basic_ofstream object.
Remarks
The first constructor initializes the base class by calling basic_ostream( sb), where sb is the stored object of class basic_filebuf< Elem, Tr>. It also initializes sb by calling basic_filebuf< Elem, Tr>.
The second and third constructors initializes the base class by calling basic_ostream( sb). It also initializes sb by calling basic_filebuf< Elem, Tr> and then sb. open( _Filename, _Mode | ios_base::out). If the latter function returns a null pointer, the constructor calls setstate( failbit).
The fourth constructor is a copy function. It initializes the object with the contents of right, treated as an rvalue reference.
Example
The following example shows how to create a basic_ofstream object and write text to it.
// basic_ofstream_ctor.cpp
// compile with: /EHsc
#include <fstream>
using namespace std;
int main(int argc, char **argv)
{
ofstream ofs("C:\\ofstream.txt");
if (!ofs.bad())
{
ofs << "Writing to a basic_ofstream object..." << endl;
ofs.close();
}
}
basic_ofstream::close
Closes a file.
void close();
Remarks
The member function calls rdbuf->close.
Example
See basic_filebuf::close for an example that uses close.
basic_ofstream::is_open
Indicates whether a file is open.
bool is_open() const;
Return Value
true if the file is open, false otherwise.
Remarks
The member function returns rdbuf -> is_open.
Example
// basic_ofstream_is_open.cpp
// compile with: /EHsc
#include <fstream>
#include <iostream>
int main( )
{
using namespace std;
ifstream file;
// Open and close with a basic_filebuf
file.rdbuf( )->open( "basic_ofstream_is_open.txt", ios::in );
file.close( );
if (file.is_open())
cout << "it's open" << endl;
else
cout << "it's closed" << endl;
}
basic_ofstream::open
Opens a file.
void open(
const char* _Filename,
ios_base::openmode _Mode = ios_base::out,
int _Prot = (int)ios_base::_Openprot);
void open(
const char* _Filename,
ios_base::openmode _Mode);
void open(
const wchar_t* _Filename,
ios_base::openmode _Mode = ios_base::out,
int _Prot = (int)ios_base::_Openprot);
void open(
const wchar_t* _Filename,
ios_base::openmode _Mode);
Parameters
_Filename
The name of the file to open.
_Mode
One of the enumerations in ios_base::openmode.
_Prot
The default file opening protection, equivalent to the shflag parameter in _fsopen, _wfsopen.
Remarks
The member function calls rdbuf -> open(_ Filename, _Mode | ios_base::out). If that function returns a null pointer, the function calls setstate( failbit).
Example
See basic_filebuf::open for an example that uses open.
basic_ofstream::operator=
Assigns the content of this stream object. This is a move assignment involving an rvalue reference that does not leave a copy behind.
basic_ofstream& operator=(basic_ofstream&& right);
Parameters
right
An rvalue reference to a basic_ofstream object.
Return Value
Returns *this.
Remarks
The member operator replaces the contents of the object by using the contents of right, treated as an rvalue reference.
basic_ofstream::rdbuf
Returns the address of the stored stream buffer.
basic_filebuf<Elem, Tr> *rdbuf
() const
Return Value
Returns the address of the stored stream buffer.
Example
See basic_filebuf::close for an example that uses rdbuf.
basic_ofstream::swap
Exchanges the contents of two basic_ofstream objects.
void swap(basic_ofstream& right);
Parameters
right
An lvalue reference to another basic_ofstream object.
Remarks
The member function exchanges the contents of this object for the contents of right.
See Also
basic_ostream Class
Thread Safety in the C++ Standard Library
iostream Programming
iostreams Conventions