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"