#include <iostream>
#include <fstream>
int main() {
std::string s;
std::ofstream fout ("abc.txt");
if (fout.is_open()) {
fout << "cyber" << std::endl << "forum";
fout.close();
} else {
std::cout << "error: failed to open file.";
return 1;
}
std::ifstream fin ("abc.txt");
fout.open("def.txt");
if (fin.is_open() && fout.is_open()) {
while (getline(fin, s)) {
fout << s << std::endl;
}
fout.close();
fin.close();
} else {
std::cout << "error: failed to open file(s).";
return 1;
}
return 0;
}