構造函數C ++中的奇怪函數調用

Question

我正在編碼一台謎題機器，並且在為機器類創建構造函數時遇到問題。 盡管必須在構造函數的參數中提供一個插件，但似乎正在調用該插件的構造函數。 這是錯誤

Machine.cpp: In constructor ‘Machine::Machine(std::list<Rotor>, Plugboard)’:
Machine.cpp:6:48: error: no matching function for call to ‘Plugboard::Plugboard()’
 Machine::Machine(list<Rotor> rots, Plugboard pb) {

Machine.cpp：

#include "Machine.h"

using namespace std;


Machine::Machine(list<Rotor> rots, Plugboard pb) {

  plugboard = pb;
  rotors = rots;

}

//give c's alphabet index
int Machine::getPosition(char c) {
  if (c >= 'A' && c <= 'Z') {
    return c - 'A';
  }
  else  {
    cout <<  "not an accepted character";
    return -1;
  }
}

//give letter at index i in alphabet
char Machine::atPosition(int i) {
  assert(i>=0 && i<=25);
  return "ABCDEFGHIJKLMNOPQRSTUVWXYZ"[i];
}

char Machine::encode(char c) {
  assert(c >= 'A' && c <= 'Z');
  //plugboard
  c = plugboard.getMatch(c);
  //forward pass through rotors
  c = rotors[0].process(c);
  //reflector
  c = Reflector::reflect(c);
  //backwards pass through rotors
  c = rotors[0].processInverse(c);
  return c;

}

Machine.h：

#ifndef MACHINE_H
#define MACHINE_H

#include <stdexcept>
#include <iostream>
#include <assert.h>
#include <list>
#include "Reflector.h"
#include "Rotor.h"
#include "Plugboard.h"

class Machine{

  public:

    Machine(std::list<Rotor> rots, Plugboard pb);   
    static int getPosition(char c);
    static char atPosition(int i);
    char encode(char c);

  private:

    std::list<Rotor> rotors;
    Plugboard plugboard;

};

#endif

Answer 1

那是因為在您的構造函數中，您首先是默認構造的plugboard ，然后將其復制分配。 只需在初始化列表中構造它即可。 並接受const & ！

Machine(const std::list<Rotor>& rots, const Plugboard& pb)
: rotors(rots)
, plugboard(pb)
{ }