Errors in my C++ work? [closed]

问题:

I am bashing my head against the wall because of my code. Basically I need to create a program that reads a file and prints out what the specification asks for. I'm stuck on this part of the specification:

For 6 marks, create a file called analyze.cpp containing a program that:

• Opens sheffield.data and skips the header lines (getline will be handy for this)

• Reads data from the file into a vector of MonthData objects

• Uses the data stored in the vector to compute and display – The year and month with the lowest minimum temperature – The year with the highest total rainfall

In the sheffield.data file is this information in a nutshell:

yyyy mm tmax tmin af rain sun degC degC days mm hours

1930 1 8.1 2.4 6 120.5 54.2

1930 2 4.4 0.6 12 22.2 29.1

1930 3 8.1 2.1 9 76.2 88.2

I have 3 files. Data.cpp, Data.hpp and analyze.cpp

Data.hpp:

#ifndef DATA_HPP
#define DATA_HPP

#include <iostream>
#include <string>
#include <cmath>

class MonthData
{
  friend std::istream& operator >> (std::istream&, MonthData&);

  public:
        //overload constructor
    MonthData(double, int, double, double, int, double, double);

        //Accessor functions
    double getYear() const    { return year; }                //returns the year
    int getMonth() const      { return month; }               //returns the month
    double getMaximum() const { return temp_maximum; }        //returns maximum temperature
    double getMinimum() const { return temp_minimum; }        //returns minimum temperature
    int getFrost() const      { return air_frost; }           //returns air frost
    double getRain() const    { return rain; }                //returns rainfall
    double getSun() const     { return sun; }                 //returns no of hours of sunshine

  private:
    double year;
    double month;
    double temp_maximum;
    double temp_minimum;
    int air_frost;
    double rain;
    double sun;
};
#endif

In my Data.cpp is this code:

#include "data.hpp"
#include <iostream>

using namespace std;

istream& operator >> (istream& in, MonthData& data)
{
  in >> data.year >> data.year >> data.temp_maximum >> data.temp_minimum >> data.air_frost >> data.rain >> data.sun;

  return in;
}

And finally in my analyze.cpp file is this code:

#include <istream>
#include <fstream>
#include <vector>

#include "data.hpp"

using namespace std;

int main()
{
 MonthData data;

  vector<MonthData> vectorData;
  ifstream file ("sheffield.data");
  string line;
  int l_num = 0;

  if (file.is_open()) {
    while (getline(file, line))
      if (l_num < 4) {
        l_num += 1;
      }
      else {
        file >> data;
        vectorData.push_back(data);  
      }  

      float MinimumDeg = vectorData[0], getMinTemp();
      int year = vectorData[0], getYear();
      for (int a =o; a < vectorData.size(); a++)
      {
        MinimumDeg = VectorData[a], getMinTemp();
        Year = VectorData[a], getYear();
      }

      cout << "Lowest year and month lowest rainfall: '\n'" << "Min Temp;" << MinimumDeg << "C '\n'" << "Year" << Year << endl;


      return 0;

}  

}     

WHY AM I GETTING THESE ERRORS?

naveed@naveed-VirtualBox:~/Documents/cw$ g++ -Wall analyze.cpp -o analyze
analyze.cpp: In function ‘int main()’:
analyze.cpp:11:13: error: no matching function for call to ‘MonthData::MonthData()’
analyze.cpp:11:13: note: candidates are:
data.hpp:14:5: note: MonthData::MonthData(double, int, double, double, int, double,   double)
data.hpp:14:5: note:   candidate expects 7 arguments, 0 provided
data.hpp:8:7: note: MonthData::MonthData(const MonthData&)
data.hpp:8:7: note:   candidate expects 1 argument, 0 provided
analyze.cpp:28:38: error: cannot convert ‘MonthData’ to ‘float’ in initialisation
analyze.cpp:29:30: error: cannot convert ‘MonthData’ to ‘int’ in initialisation
analyze.cpp:30:19: error: ‘o’ was not declared in this scope
analyze.cpp:30:42: warning: comparison between signed and unsigned integer expressions     [-Wsign-compare]
analyze.cpp:32:22: error: ‘VectorData’ was not declared in this scope
analyze.cpp:33:9: error: ‘Year’ was not declared in this scope 
analyze.cpp:36:115: error: ‘Year’ was not declared in this scope
analyze.cpp:29:11: warning: unused variable ‘year’ [-Wunused-variable]

回答1:

Your MonthData class lacks a default constructor.

error: no matching function for call to ‘MonthData::MonthData()’

The code you wrote in main() constructs a MonthData with no arguments, that is the reason for the error above (and probably std::vector< MonthData > also needs a default constructor):

MonthData data;

So provide a default constructor.

回答2:

You are calling the default constructor here:

 MonthData data;

But you didn't implement one..

You created a constructor that receives parameters to read the file to variables and then instantiate your MonthData data(...);