How do you write a c plus plus program that prints an error message and exits when an ifstream cannot be opened?

Answer 1

#include<iostream>

#include<fstream>

#include<string>

#include<vector>

struct data

{

std::string lastname;

std::string firstname;

double weight;

};

std::istream& operator>> (std::istream& is, data& d)

{

return is >> d.lastname >> d.firstname >> d.weight;

}

std::ostream& operator<< (std::ostream& os, const data& d)

{

return os << d.lastname << ' ' << d.firstname << ' ' << d.weight;

}

int main()

{

std::cout << "Enter filename: ";

std::string filename;

std::cin >> filename;

std::ifstream infile (filename);

if (infile.bad())

{

std::cerr << filename << " could not be opened!\n";

return -1;

}

std::vector<data> v;

char c;

while (infile >> c)

{

infile.putback (c);

data d;

infile >> d;

v.push_back (d);

}

infile.close();

for (auto d : v)

std::cout << d << '\n';

}