A simple gist showing processing of a textfile

main.cpp

#include <set>
#include <string>
#include <iostream>
#include <fstream>
#include <sstream>

struct user {
	std::string name;
	std::string email;
	std::string password;
};

// overload the "<" operator so that a user type can be used 
// in a `std::set`
inline bool operator<(const user& x, const user& y) {
	return x.email < y.email && x.name < y.name;
}

// declare the prototype of the function
std::set<user> readFile(const std::string&);

int main(int argc, char **argv) {

	if (argc < 2) {
		std::cout << "ERROR: file path missing" << std::endl;
		return 1;
	}

	std::set<user> users = readFile(std::string(argv[1]));

	std::cout << "Numero Usuarios: " << users.size() << std::endl;

	for (auto user : users) {
		std::cout << "Nombre: " << user.name << std::endl;
		std::cout << "Mail: " << user.email << std::endl;
		std::cout << std::endl;
	}

	return 0;
}

/**
 * 
 */
std::set<user> readFile(const std::string& filePath) {

	std::ifstream file(filePath);

	std::set<user> users;

	if (!file) {
		return users;
	}

	std::string line;
	while (std::getline(file, line)) {

		// skip if empty
		if ( line.empty() ) {
			continue;
		}

		std::istringstream linestream(line);

		user u = { "", "", "" };

		if ( !(linestream >> u.name) ) {
			continue;
		}

		if ( !(linestream >> u.email) ) {
			continue;
		}

		if ( !(linestream >> u.password) ) {
			continue;
		}

		users.insert(u);
	}

	file.close();

	return users;
}

testdata.txt

USUARIO_NOM_1 user1@example.com USUARIO_CONTRASENYA_1 
USUARIO_NOM_2 user2@example.com USUARIO_CONTRASENYA_2 

USUARIO_NOM_4 user4@example.com
USUARIO_NOM_3 user3@example.com USUARIO_CONTRASENYA_3 
USUARIO_NOM_4 user4@example.com USUARIO_CONTRASENYA_4