CODEWITHSUNDEEP
c++classpointersaccessor
Rob Schneider
Rob Schneider

Reputation: 165

Calling member function with reference to pointer

I have a class CaloReader that creates a pointer _calo to an object called Calorimeter containing a grid of cells with an ID number. This pointer is then used to set an ID number to each cell. Futhermore, I have a accessor const Calorimeter& calo() that returns a reference of this pointer. Now, I want to create a function dumpReadoutMap() that prints out all ID numbers of all cells. The function is called from my main file as follows:

#include <iostream>
#include "CaloCell.hh"
#include "CaloGrid.hh"
#include "Point.hh"
#include "Calorimeter.hh"
#include "CaloReader.hh"

int main(){

    CaloReader r("calo.dat");
    r.calo().dumpReadoutMap();

}

The problem with my code is that the complirer gives the following error:

error: ‘const class Calorimeter’ has no member named ‘dumpReadoutMap’
 r.calo().dumpReadoutMap();

The only relevant file for this question is the below as the other ones are correct and cannot be changed.

#ifndef CALOREADER_HH
#define CALOREADER_HH

#include <iostream>
#include <fstream>
#include "Calorimeter.hh"

#include "CaloReaderException.hh"
#include <string>
#include <iomanip>

class CaloReader {

public:

    CaloReader(const char* file): _file(file) {

        Calorimeter* _calo = 0;
        ifstream _file(file);

        std::string word;
        _file >> word;

        _file >> word; //Reads in next word.
        if(word=="SIZE") {
            int size_x;
            int size_y;
            _file >> size_x;
            _file >> size_y;

            _calo = new Calorimeter(size_x,size_y);

        }
        _file >> word;

        while(word=="POSITION") {
            int readoutID;
            int ix;
            int iy;
            _file >> readoutID >> ix >> iy;
            //std::cout << word << " " << readoutID << " " << ix << " " << iy << std::endl;
            _calo->grid().cell(ix,iy)->setID(readoutID);

            _file >> word;
        }
    }

    ~CaloReader() {}

    const Calorimeter& calo() const {
        return *_calo;
    }

    void dumpReadoutMap(std::ostream& os = std::cout) {


        for(int x =0; x<size_x; x++) {
            for(int y=0; y<size_y; y++) {
                os << std::setw(6) << grid().cell(x,y)->getID();
            }
            os << std::endl;
        }
    }


private:

    Calorimeter* _calo;
    std::ifstream _file;
    std::string word;

};
#endif

Upvotes: 1

Views: 425

Answers (2)

WaltK
WaltK

Reputation: 774

Since calo() returns a const reference, you can't call a non-const member function with it. It's disappointing the error message doesn't explain clearly what the error is.

Upvotes: 0

Serge Ballesta
Serge Ballesta

Reputation: 148900

dumpReadoutMap is a method in CaloReader class. So it must be called from a CaloReader object. You should use:

CaloReader r("calo.dat");
r.dumpReadoutMap();

Upvotes: 1

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