NAME¶

std::basic_ifstream::swap - std::basic_ifstream::swap

Synopsis¶

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