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std::swap(std::basic_ifstream)

From cppreference.com
< cpp‎ | io‎ | basic ifstream
 
 
 
 
template< class CharT, class Traits >
void swap( basic_ifstream<CharT, Traits>& lhs, basic_ifstream<CharT, Traits>& rhs );

Specializes the std::swap algorithm for std::basic_ifstream. Exchanges the state of lhs with that of rhs. Effectively calls lhs.swap(rhs).

Contents

[edit] Parameters

lhs, rhs - streams whose state to swap

[edit] Return value

(none)

[edit] Exceptions

May throw implementation-defined exceptions.

[edit] Example

#include <fstream>
#include <iostream>
#include <string>
 
bool create_stream(std::ifstream& fs)
{
    try
    {
        std::string some_name = "/tmp/test_file.txt";
        std::ios_base::openmode some_flags = fs.trunc; // | other flags
 
        if (std::ifstream ts{some_name, some_flags}; ts.is_open())
        {
            std::swap(ts, fs); // stream objects are not copyable => swap
            return true;
        }
    }
    catch (...)
    {
        std::cout << "Exception!\n";
    }
    return false;
}
 
int main()
{
    if (std::ifstream fs; create_stream(fs))
    {
        // use fs stream
    }
}

[edit] See also

(C++11)
swaps two file streams
(public member function) [edit]