C++ import data from a .txt file via a string pointer - c++

Question

players.txt
2
Zlatan
Ibrahimovic
1981
4
20130110
20130117
20130122
20130208
Yohan
Cabaye
1986
1
20130301
Main.cpp
#include <iostream>
#include <string>
#include <fstream>
using namespace std;
int main()
{
ifstream pFile("players.txt");
int numberOfPlayers;
string firstName;
string lastName;
int birthYear;
int numberOfMatches = 0;
string *matchDates = NULL;
matchDates = new string[];
while (pFile >> numberOfPlayers >> firstName >> lastName >> birthYear >> numberOfMatches >> matchDates)
{
for(int i = 0; i < numberOfPlayers; i++)
{
cout << firstName << endl;
cout << lastName << endl;
cout << birthYear << endl;
for(int i = 0; i < numberOfMatches; i++)
{
cout << matchDates[i] << endl;
}
}
}
delete[] matchDates;
getchar();
return 0;
}
So I want to import data from a textfile, e.g. soccer players as above or anything else, like hockey players etc. The point is to be able to use this code for all kind of sports aka it's not set to like 12 players max, amount of players should be dynamic. Well I'm already stuck here with what I thought was a dynamic array (matchDates) but I've been told that it's not and is still a static array.
matchDates should also be dynamic because some players could've 20 mathcdates, another could have five, another three and so on. In my example zlatan has four and youhan one.
Well my problem appear on line 20, posted below:
while (pFile >> numberOfPlayers >> firstName >> lastName >> birthYear >> numberOfMatches >> matchDates)
Error message when I hover over the bolded ">>" (which is underlined with red in VS)
Error no operator ">>" matches these operands
operand types are: std::basic_istream> >> std::string *
I want to print out all matchdates but it doesn't work and I'm very sure it's something to do with matchDates.
Thanks in advance and regards Adam

Answer 1

Use C++ class for player, stop using new and override stream operator.
See the code in action here
#include <iostream>
#include <string>
#include <deque>
#include <fstream>
#include <algorithm>
#include <iterator>
using namespace std;
class Player
{
public:
Player() : firstName(""), lastName(""), birthYear(0){}
~Player() {}
//copy ctor by default
// Operator Overloaders
friend ostream &operator <<(ostream &output, const Player p);
friend istream &operator >>(istream &input, Player &p);
private:
string firstName;
string lastName;
int birthYear;
deque<string> matchDates;
};
ostream& operator <<( ostream& output, const Player p )
{
output << p.firstName << " " << p.lastName << " etc ...";
return output;
}
istream& operator >>( istream& input, Player &p )
{
input >> p.firstName;
input >> p.lastName;
input >> p.birthYear;
int nbMatch = 0; input >> nbMatch;
for(int i = 0 ; i < nbMatch ; ++i) {
string match_date; input >> match_date;
p.matchDates.push_back(match_date);
}
return input;
}//*/
int main()
{
//ifstream pFile("players.txt");
int numberOfPlayers;
deque<Player> players;
cin >> numberOfPlayers; int i = 0;
while( i < numberOfPlayers)
{
Player p;
cin >> p;
players.push_back(p);
i++;
}
std::ostream_iterator< Player > output( cout, "\n" );
cout << "What we pushed into our deque: ";
copy( players.begin(), players.end(), output );
getchar();
return 0;
}

Answer 2

The Problem
This is the error Clang gives me:
error: invalid operands to binary expression ('istream' and 'string *')
Then it goes on to list the various overloads of operator>>() and why a right-hand operand of type std::string* cannot convert to respective right-hand types. This is expected because there are no overloads of operator>>() that take a pointer or array of that type.
Solution
When reading into an array, you normally read into "temporary" objects and copy that to the array. For example:
#include <iostream>
int main()
{
int array[5];
for (int i = 0, temp; i < 5 && std::cin >> temp; ++i)
{
array[i] = temp;
}
}
But in your case, you initialized your array with the following line which I assume to be an attempt to create an indefinitely-sized array:
matchDates = new string[];
I don't know about Visual Studio, but on Clang I got the following error:
Error(s):
error: expected expression
int* j = new int[];
^
1 error generated
Dynamically-sized arrays are not possible in C++. If you need an array that will grow in size, consider using a std::vector. You would need to call push_back() to insert elements.

Answer 3

You can put things at one line to ease the code for your eye but don't over do it. Take a 'record' as a one record, so you can say.
An array doesn't have the >> operator.
Would go for user 0x499602D2 his answer but I may not upvote nor comment yet, so I put it here as I already answered. ;)
#include <iostream>
#include <string>
#include <fstream>
using namespace std;
int main()
{
ifstream pFile( "players.txt" );
int numberOfPlayers;
string firstName;
string lastName;
int birthYear;
int numberOfMatches = 0;
while( pFile >> numberOfPlayers )
{
for( int i = 0; i < numberOfPlayers; i++ )
{
pFile >> firstName >> lastName >> birthYear >> numberOfMatches;
cout << firstName << endl;
cout << lastName << endl;
cout << birthYear << endl;
for( int i = 0; i < numberOfMatches; i++ )
{
string date;
pFile >> date;
cout << date << endl;
}
}
}
getchar();
return 0;
}
To maintain the data you can createa a struct (or class). The second while loop is just to print out while the first gets the data.
#include <iostream>
#include <string>
#include <fstream>
#include <vector>
using namespace std;
struct Player
{
string firstName;
string lastName;
int birthYear;
std::vector<string> matchDates;
};
int main()
{
ifstream pFile( "players.txt" );
int numberOfPlayers;
int numberOfMatches = 0;
std::vector<Player> players;
// fill the vector players
while( pFile >> numberOfPlayers )
{
for( int i = 0; i < numberOfPlayers; i++ )
{
// create player struct and fill it
Player player;
pFile >> player.firstName >> player.lastName >> player.birthYear >> numberOfMatches;
for( int i = 0; i < numberOfMatches; i++ )
{
string date;
pFile >> date;
player.matchDates.push_back( date );
}
// add it to the vector
players.push_back( player );
}
}
// print out the values
std::vector<Player>::iterator iterPlayer = players.begin(),
endPlayer = players.end;
while( iterPlayer != endPlayer )
{
Player player = *iterPlayer;
cout << player.firstName << endl;
cout << player.lastName << endl;
cout << player.birthYear << endl;
std::vector<string>::iterator iterDates = player.matchDates.begin(),
endDates = player.matchDates.end;
while( iterDates != endDates )
{
string date = *iterDates;
cout << date << endl;
}
}
getchar();
return 0;
}