c++11 standard template (STL) (std::basic_ofstream) (5)

defined in the header file <fstream>

template<     class CharT,     class Traits = std::char_traits<CharT> > class basic_ofstream : public std::basic_ostream<CharT, Traits>

 Class Template basic_ofstreamImplements high-level stream-based output operations on files. It gives the high-level interface of std::basic_ostream to a file-based stream buffer ( std::basic_filebuf ).

std::basic_ofstreamTypical implementations keep only one non-exported member: an instance of std::basic_filebuf<CharT, Traits> .

 Two specializations are also defined for common character types:

type	definition
ofstream	basic_ofstream<char>
wofstream	basic_ofstream<wchar_t>

file operation

close associated file

std::basic_ofstream<CharT,Traits>::close

void close();

Close the associated file.

Equivalently calls rdbuf()->close(). If an error occurred during the operation, setstate(failbit) is called.

parameter

(none)

return value

(none)

Notice

This function is called as the destructor of basic_ofstream when the stream object leaves the scope, usually not called directly.

call example

#include <fstream>
#include <utility>
#include <string>
#include <iostream>

int main()
{
    std::ofstream ofstream1("test1.txt", std::ios::in);
    std::ofstream ofstream2("test2.txt", std::ios::in);
    std::ofstream ofstream3("test3.txt", std::ios::in);
    std::cout << "ofstream1 is: " 
              << (ofstream1.is_open() ? "true" : "false") << std::endl;
    std::cout << "ofstream2 is: " 
              << (ofstream2.is_open() ? "true" : "false") << std::endl;
    std::cout << "ofstream3 is: " 
              << (ofstream3.is_open() ? "true" : "false") << std::endl;

    std::cout << std::endl;
    std::cout << "std::ofstream close" << std::endl;
    ofstream1.close();
    ofstream2.close();
    ofstream3.close();

    std::cout << std::endl;

    std::cout << "ofstream1 is: "
              << (ofstream1.is_open() ? "true" : "false") << std::endl;
    std::cout << "ofstream2 is: "
              << (ofstream2.is_open() ? "true" : "false") << std::endl;
    std::cout << "ofstream3 is: "
              << (ofstream3.is_open() ? "true" : "false") << std::endl;

    std::cout << std::endl;
    return 0;
}

output

 

non-member function

specialization of the std::swap algorithm

std::swap(std::basic_ofstream)

template< class CharT, class Traits > void swap( basic_ofstream<CharT,Traits> &lhs, basic_ofstream<CharT,Traits> &rhs );

 Specializes the std::swap algorithm for std::basic_ofstream. Swap the state of lhsand rhs. Equivalently call lhs.swap(rhs).

parameter

lhs, rhs

-

stream to exchange state

return value

(none)

abnormal

(none)

call example

#include <fstream>
#include <utility>
#include <string>
#include <iostream>

int main()
{
    std::ofstream ofstream1("test1.txt", std::ios::out);
    std::cout << "ofstream1 is: "
              << (ofstream1 ? "true" : "false") << std::endl;
    std::ofstream ofstream2("test2.txt", std::ios::out);
    std::cout << "ofstream2 is: "
              << (ofstream2 ? "true" : "false") << std::endl;
    std::cout << std::endl;

    ofstream1 << "hello 1" << " ";
    ofstream2 << "hello 2" << " ";
    //为 std::basic_ofstream 特化 std::swap 算法。
    //交换 lhs 与 rhs 的状态。等效地调用 lhs.swap(rhs) 。
    std::cout << "std::swap(ofstream1, ofstream2) " << std::endl;
    std::swap(ofstream1, ofstream2);
    ofstream1 << "hello 1" << " ";
    ofstream2 << "hello 2" << " ";
    ofstream1.close();
    ofstream2.close();
    std::cout << std::endl;

    std::ifstream ifstream1("test1.txt", std::ios::in);
    std::cout << "ifstream1 is: "
              << (ifstream1.is_open() ? "true" : "false") << std::endl;
    if (ifstream1.is_open())
    {
        std::cout << ifstream1.rdbuf() << std::endl;
    }
    std::cout << std::endl;

    std::ifstream ifstream2("test2.txt", std::ios::in);
    std::cout << "ifstream2 is: "
              << (ifstream2.is_open() ? "true" : "false") << std::endl;
    if (ifstream2.is_open())
    {
        std::cout << ifstream2.rdbuf() << std::endl;
    }
    std::cout << std::endl;

    return 0;
}

output