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#include <fstream>
#include <iostream>
#include <string>
using namespace std;
int main()
{
fstream rw("fname", ios::out | ios::in);
if (!rw) // file didn't exist yet
{
rw.clear(); // try again, creating it using ios::trunc
rw.open("fname", ios::out | ios::trunc | ios::in);
}
if (!rw) // can't even create it: bail out
{
cerr << "Opening `fname' failed miserably" << '\n';
return 1;
}
cerr << "We're at: " << rw.tellp() << '\n';
// write something
rw << "Hello world" << '\n';
rw.seekg(0); // go back and read what's written
string s;
getline(rw, s);
cout << "Read: " << s << '\n';
}
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