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. For more information, see basic_filebuf.

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 an 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

Constructor	Description
basic_ofstream	Creates an object of type basic_ofstream.

Member functions

Member function	Description
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	Description
operator=	Assigns the content of this stream object. This is a move assignment involving an rvalue reference that doesn't 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 initialize 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.

For more information, see basic_ostream, open, and setstate.

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. For more information, see rdbuf and 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. For more information, see rdbuf and 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).

For more information, see rdbuf, open, and setstate.

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 doesn't 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