#include #include #include #include #include #include struct Node { unsigned int id; unsigned int phone; friend std::ostream& operator << ( std::ostream&, const Node& ); }; std::ostream& operator << ( std::ostream& os, const Node& obj ) { os << "Node: " << obj.id << " -> " << obj.phone; return os; } class SingleList { public: SingleList( const std::string& path ) { this->read_in( path ); } void assign( const std::string& path ) { this->read_in( path ); } private: void read_in( const std::string path ) { std::ifstream file( path ); if ( !file.is_open() ) { return; } std::string s; while ( std::getline( file, s ) ) { // set up stringstream object std::stringstream ss( s ); // temporary node to store the extracted values Node _tmp; ss >> _tmp.id; // extract id ss.get(); // extract comma ss >> _tmp.phone; // extract phone number // add entry to the list this->mList.push_front ( std::move( _tmp ) ); } file.close(); } std::forward_list< Node > mList; friend std::ostream& operator << ( std::ostream&, const SingleList& ); }; std::ostream& operator << ( std::ostream& os, const SingleList& obj ) { for ( const auto& node : obj.mList ) { os << node << std::endl; } return os; } int main() { std::ofstream data( "data.txt" ); if ( !data.is_open() ) { return 1; } data << "1, 12345\n" << "2, 23456\n" << "3, 34567\n"; data.close(); std::cout << SingleList( "data.txt" ) << std::endl; return 0; }

[Q&A] File to List