Question

我重载了Extraction和Insertion运算符。但是现在无论何时在main.cpp中调用它们，编译器都会告诉我存在一个模糊错误。我有点理解歧义错误是什么，但我不能为我的生活弄清楚它为什么会发生。

如果有帮助，我会使用g ++编译器和LLDB调试器。

错误：

/Users/Final Project/ms1.cpp:147:12: error: use of overloaded operator '<<' is ambiguous (with operand types 'ostream' (aka 'basic_ostream<char>') and 'oop244::Date')
      cout << A << " is not equal to " << B << " but operator!= returns otherwise!" << endl;
      ~~~~ ^  ~
/Users/Final Project/Date.h:57:17: note: candidate function
  std::ostream& operator<<(std::ostream os, Date& Dob);

接下来是十亿其他类似的错误。

我的主要（发生错误的地方）：

#include <iostream>
#include <cstring>
#include "Date.h"
#include "Date.cpp"
#include "general.h"
using namespace std;
using namespace oop244;
bool equalDates(const char* A, const char* B);
int main(){
  int ret = 0;
  char confirm[2000];
  bool ok = true;
  Date A(2018, 10, 18);
  Date B;
......
......
A = Date(2018, 10, 17);
  if (ok){
    cout << "testing operator!=" << endl;
    if (A != B){
      cout << "passed!" << endl;
    }
    else{
      cout << A << " is not equal to " << B << " but operator!= returns otherwise!" << endl;
      ok = false;
    }
  }

班级宣言

#ifndef __244_DATE_H__
#define __244_DATE_H__
// header file includes
#include "general.h"
#include <string>
#include <iostream>

namespace oop244{

  class Date{
  private:
    // private member variables
    int _year;
    int _mon;
    int _day;
    int _readErrorCode;

    // private member functions and setters
    int value()const;
    void setErrCode(int errCode);
.....
.....

  public:
    // constructors
    Date();
    Date(int,int,int);
    ~Date();

    std::ostream& write(std::ostream& ostr, Date& dob);
    std::istream& read(std::istream& istr, Date& dob);

  };

  std::istream& operator>>(std::istream is, Date& dob);
  std::ostream& operator<<(std::ostream os, Date& dob);

    }
#endif

类函数定义

#include "general.h"
#include "Date.h"
#include <iomanip>
#include <iostream>

using namespace std;
namespace oop244{

  // constructors
  Date::Date()
  {
    _year=0;
    _mon=0;
    _day=0;
    _readErrorCode=NO_ERROR;
  }

  Date::Date(int year,int month, int day)
  {
    _year=year;
    _mon=month;
    _day=day;
    _readErrorCode=NO_ERROR;
  }

  Date::~Date() {}

  // member functions

  void Date::setErrCode(int errCode)
  {
    _readErrorCode=errCode;
  }

  void Date::passErr(int errCode)
  {
    setErrCode(errCode);
  }
.....
.....
  int Date::getErrCode() const
  {
    return _readErrorCode;
  }


  std::istream& Date::read(std::istream& istr, Date& dob) 
  {
    char y[5],m[3],d[3];
    int year,month,day;

    istr.getline(y,5,'/');
    istr.getline(m,3,'/');
    istr.getline(d,3,'/');

    year=atoi(y);
    month=atoi(m);
    day=atoi(d);

    Date temp (year,month,day);

    if (year>=2000 && year<=2030)
      dob.passErr(YEAR_ERROR);
    else if (month+=1 && month<=12)
      dob.passErr(MON_ERROR);
    else if (day>=1 && day<=31)
      dob.passErr(DAY_ERROR);
    else
    {
      dob.passErr(NO_ERROR);
      dob=temp;
    }
    return istr;
  }

  std::ostream& Date::write(std::ostream& ostr, Date& dob)
  {
    int year=dob.getYear();
    int month=dob.getMonth();
    int day=dob.getDay();
    ostr<<year<<"/"<<month<<"/"<<day<<endl;
    return ostr;
  }

  // non-memeber operator overloads
std::istream& operator>>(std::istream& is, Date& dob)
{
  dob.read(is,dob);
  return is;
}

std::ostream& operator<<(std::ostream& os, Date& dob)
{
  dob.write(os,dob);
  return os;
}

}

对不起超长的帖子。我的智慧结束了。我提前感谢你们。

Answer 1

看起来像运算符＆gt;＆gt;的函数原型和运算符＆lt;＆lt;不要将他们的参数与定义相匹配。换句话说：

std::ostream& operator<<(std::ostream os, Date& dob);

你头文件中的

缺少＆amp;对于std :: ostream。对于运算符＆gt;＆gt;。

也是如此

（C ++）错误：使用重载运算符＆＃39;＆lt;＆lt;＆lt;＆＃是不明确的（操作数类型＆＃39; ostream＆＃39;（又名＆＃39; basic_ostream <char>＆＃39;）</char>

1 个答案: