c++ - 创建值并将值插入对象的问题

Question

我在这里尝试做的是创建对象并将它们存储在 vector 中，并通过获取每一行通过文件为这些对象分配值。

例如: 我有一个 Player 类，其值为 name、classType、strength、endurance 和 id

然后通过文本或 cfg 文件，我想为这些变量中的每一个赋值并从中创建一个对象，然后将它们放入一个 vector 中。

我的问题:

如何将文本文件中的值赋给对象，然后将该对象放入 vector 中？

问题:

我收到了一大堆错误消息，我将在下面显示这些消息。

我希望的结果是什么:

将文件中写入的文本创建为一个对象，并将该对象插入一个 vector 。

这是我在下面尝试过的。

播放器.txt

example1 Scribe 3 6 1
example2 Cursed 3 3 2
example3 Thief 3 1 3
example4 Paladin 9 5 4
example5 Hobo 3 7 5

依赖关系.h

#ifndef DEPENDENCIES_H
#define DEPENDENCIES_H
 std::istream& operator>>(std::istream& str, Player& player) {
    std::string line;
    if (std::getline(str, line)) {
       std::stringstream lineStream(line);

       std::string name;
       std::string classType;
       int         strength;
       int         endurance;
       int         id;

       if (lineStream >> name >> classType >> strength >> endurance >> id) {
           // Set up the player object.
           player = Player(name, classType, strength, endurance, id);
       }
       else {
           // Error when reading player characteristics from line.
           // Need to set the errror state of the stream.
           str.setstate(std::ios::failbit);
       }
    }
    return str;
}

std::vector<Player> getPlayers() {
    std::ifstream                 playerFile("Player.txt");
    std::istream_iterator<Player> playerIter(playerFile);
    std::istream_iterator<Player> end;

    return std::vector<Player>(playerIter, end);
}
#endif

main.cpp

#include <iostream>
#include <string>
#include <time.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <math.h>
#include <vector>
#include <iterator>
#include <sstream>
#include <fstream>
#include "DEPENDENCIES.h"

int main() {

std::vector<Player> allPlayers(getPlayers());
//Do whatever with the vector here

return 0;
}

promise 的错误

In file included from /usr/local/include/c++/7.1.0/iterator:66:0,
                 from main.cpp:18:
/usr/local/include/c++/7.1.0/bits/stream_iterator.h: In instantiation of 'constexpr std::istream_iterator<_Tp, _CharT, _Traits, _Dist>::istream_iterator() [with _Tp = Player; _CharT = char; _Traits = std::char_traits<char>; _Dist = long int]':
DEPENDENCIES.h:79:35:   required from here
/usr/local/include/c++/7.1.0/bits/stream_iterator.h:65:46: error: no matching function for call to 'Player::Player()'
       : _M_stream(0), _M_value(), _M_ok(false) {}
                                              ^
In file included from main.cpp:21:0:
DEPENDENCIES.h:23:3: note: candidate: Player::Player(std::__cxx11::string, std::__cxx11::string, int, int, int)
   Player(std::string inpName, std::string inpClassType, int inpStrength, int inpEndurance, int inpId) {
   ^~~~~~
DEPENDENCIES.h:23:3: note:   candidate expects 5 arguments, 0 provided
DEPENDENCIES.h:11:7: note: candidate: Player::Player(const Player&)
 class Player {
       ^~~~~~
DEPENDENCIES.h:11:7: note:   candidate expects 1 argument, 0 provided
DEPENDENCIES.h:11:7: note: candidate: Player::Player(Player&&)
DEPENDENCIES.h:11:7: note:   candidate expects 1 argument, 0 provided
In file included from /usr/local/include/c++/7.1.0/iterator:66:0,
                 from main.cpp:18:
/usr/local/include/c++/7.1.0/bits/stream_iterator.h: In instantiation of 'std::istream_iterator<_Tp, _CharT, _Traits, _Dist>::istream_iterator(std::istream_iterator<_Tp, _CharT, _Traits, _Dist>::istream_type&) [with _Tp = Player; _CharT = char; _Traits = std::char_traits<char>; _Dist = long int; std::istream_iterator<_Tp, _CharT, _Traits, _Dist>::istream_type = std::basic_istream<char>]':
DEPENDENCIES.h:78:56:   required from here
/usr/local/include/c++/7.1.0/bits/stream_iterator.h:69:40: error: no matching function for call to 'Player::Player()'
       : _M_stream(std::__addressof(__s))
                                        ^
In file included from main.cpp:21:0:
DEPENDENCIES.h:23:3: note: candidate: Player::Player(std::__cxx11::string, std::__cxx11::string, int, int, int)
   Player(std::string inpName, std::string inpClassType, int inpStrength, int inpEndurance, int inpId) {
   ^~~~~~
DEPENDENCIES.h:23:3: note:   candidate expects 5 arguments, 0 provided
DEPENDENCIES.h:11:7: note: candidate: Player::Player(const Player&)
 class Player {
       ^~~~~~
DEPENDENCIES.h:11:7: note:   candidate expects 1 argument, 0 provided
DEPENDENCIES.h:11:7: note: candidate: Player::Player(Player&&)
DEPENDENCIES.h:11:7: note:   candidate expects 1 argument, 0 provided

exit status 1

Answer 1

错误消息的关键部分是:

error: no matching function for call to 'Player::Player()'

如果我们阅读例如this std::istream_iterator reference我们会看到

T must meet the DefaultConstructible, [...] requirements.

由于您的 Player 类没有默认构造函数，您不能将它与 std::istream_iterator 一起使用。

简单的解决方案当然是创建一个默认构造函数。它甚至可以像这样简单

Player() = default;