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