std::basic_ifstream<CharT,Traits>::swap

 

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std::basic_ifstream

Member functions

basic_ifstream::basic_ifstream

basic_ifstream::operator= (C++11)

basic_ifstream::swap (C++11)

basic_ifstream::rdbuf

basic_ifstream::native_handle (C++26)

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Non-member functions

swap(std::basic_ifstream) (C++11)

 

void swap( basic_ifstream& other );		(since C++11)

Exchanges the state of the stream with those of other.

This is done by calling basic_istream<CharT, Traits>::swap(other) and rdbuf()->swap(other.rdbuf()).

Parameters

other

-

stream to exchange the state with

Return value

(none)

Exceptions

May throw implementation-defined exceptions.

Example

Run this code

#include <fstream>
#include <iomanip>
#include <iostream>
#include <string>
 
bool create_stream(std::fstream& fs, const std::string& path) {
    try {
        std::fstream fst { path, std::ios::trunc | std::ios::in | std::ios::out };
        if (fst.is_open()) {
            fst.swap( fs );
            return true;
        }
    } catch (...) {
        std::cout << "Exception!\n";
    }
    return false;
}
 
void use_stream(std::fstream& fs) {
    fs.seekg(0);
    std::string data;
    fs >> data;
    std::cout << "data: " << std::quoted(data) << '\n';
}
 
int main() {
    std::fstream fs;
    std::string path = "/tmp/test_file.txt";
    if (create_stream(fs, path)) {
        fs.write(path.c_str(), path.length());
        use_stream(fs);
    }
}

Possible output:

data: "/tmp/test_file.txt"

See also

operator= (C++11)	moves the file stream (public member function)
swap (C++11)	swaps two basic_filebuf objects (public member function of std::basic_filebuf<CharT,Traits>)