Nate Nate - 4 months ago 17
C++ Question

Print function for class c++

I want to write a print function for a class AutoData that has information about cars in it. With this print function, I would ideally like to print out a vector that contains many different class objects. I have already written get functions for each element of the objects, but I am still a bit unsure of how to go about using those to write a function to print out the data in the following format:

mpg:cylinders:displacement:horsepower:weight:acceleration:modelYear:origin:carName


For example:

10.0:8:360.0:215.0:4615.:14.0:70:1:ford f250
10.0:8:307.0:200.0:4376.:15.0:70:1:chevy c20
11.0:8:318.0:210.0:4382.:13.5:70:1:dodge d200


The class is:

#include <string>
#include <vector>
#include <iostream>

using namespace std;

class AutoData {

public:
AutoData()
{
mpg = 0;
cylinders = 0;
displacement = 0;
horsepower = 0;
weight = 0;
acceleration = 0;
modelYear = 0;
origin = 0;
carName = "";
}

AutoData( const AutoData & rhs)
{
setAuto(rhs.mpg, rhs.cylinders, rhs.displacement, rhs.horsepower, rhs.weight, rhs.acceleration, rhs.modelYear, rhs.origin, rhs.carName);
}

void setAuto(float mp, int cy, float di, float ho, float we, float ac, int mo, int o, string ca)
{
mpg = mp;
cylinders = cy;
displacement = di;
horsepower = ho;
weight = we;
acceleration = ac;
modelYear = mo;
origin = o;
carName = ca;
}

const float & getmpg( ) const
{
return mpg;
}

const int & getcylinders( ) const
{
return cylinders;
}

const float & getdisplacement( ) const
{
return displacement;
}

const float & gethorsepower( ) const
{
return horsepower;
}

const float & getweight( ) const
{
return weight;
}

const float & getacceleration( ) const
{
return acceleration;
}

const int & getmodelYear( ) const
{
return modelYear;
}

const int & getorigin( ) const
{
return origin;
}

const string & getcarName( ) const
{
return carName;
}

bool operator == (const AutoData & rhs ) const
{
if( getmpg( ) == rhs.getmpg( ) )
{
return gethorsepower( ) == rhs.gethorsepower( );
}

else
{
return false;
}
}

bool operator > ( const AutoData & rhs ) const
{
if( rhs.getmpg( ) > getmpg( ) )
{
return true;
}

else if( getmpg( ) == rhs.getmpg( ) )
{
if( rhs.gethorsepower( ) > gethorsepower( ) )
{
return true;
}
}

else
{
return false;
}
}


private:
float mpg;
int cylinders;
float displacement;
float horsepower;
float weight;
float acceleration;
int modelYear;
int origin;
string carName;
};


Any help/advice anyone can provide would be very much appreciated!! Thanks

Answer

I you want to be able to something like std::cout << AutoData() ;, you need to overload operator<< :

std::ostream& operator<< (std::ostream & out, AutoData const& data) {
    out << data.getmpg() << ":" ;
    out << etc... 
    return out ;
}

This function goes out of the class scope, and because you've created getters for all attributes, this function does not have to be a friend of your class.

Then you can do :

AutoData myAuto ;
std::cout << myAuto << std::endl ;
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