C++ Program Bug need Help

[homing]

Hey,

I've got a problem in the following program:
(actually it's a little simulation of another program, so i've chosen really bad variable names/function names)

My main target is:

1) to create an object with width and length createObject(float,float)
2) add the Object to a vector (group)
3) to draw( cout ) all objects in the vector (cout width and length of the object)
4) straight edit width and legth of any object in the list(x,y)

task 1-3 is working fine.
but somehow when i try to set a new x and y in my code, it wont get changed in my vectors object (start values remain). anyone can help?

here is the code:

//main

#include <QCoreApplication>
#include <iostream>
#include <vector>
#include <renderer.h>
#include "obj.h"
int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    renderer r;
    r.creatObject(555,153);

    r.draw();


    cout << "------------MOVE SECTION------------ // NOT WORKING //" << endl;

    r.getObj(0).setX(10);           //set x value of the object by index
    r.getObj(0).setY(55);           //set y value of the object by index
    r.getVector().at(0).setX(888);     //get vector -> object by index -> set x value
    r.getVector().at(0).setY(999);     //get vector -> object by index -> set y value

    r.draw();
    //output is still 555 and 153



    return a.exec();
}



//something like a controller class

#include "renderer.h"
#include <iostream>

using namespace std;

renderer::renderer()
{

}


//create an object and its x and y values 
void renderer::creatObject(float x, float y)
{
    obj o;
    o.setX(x);
    o.setY(y);
    
    //add it to the group(vector)

    //g -> Group g; in header
    g.add(o);
}


//call the group function gdraw()
void renderer::draw()
{
    //g -> Group g; in header
    g.gdraw();
}

//return vector/group size
int renderer::size()
{
    //g -> Group g; in header
    return g.size();
}


// get object straight by index
obj renderer::getObj(int index)
{
    return g.get(index);
}


//get whole vector
std::vector<obj> renderer::getVector()
{
    return g.getVector();
}


//group of objects class  -> drived from obj class
#include "group.h"

group::group()
{

}

void group::add(obj ob)
{
    //o -> std::vector<obj> o; in header
    o.push_back(ob);
}

obj group::get(int location)
{
     //o -> std::vector<obj> o; in header
    return o.at(location);
}

void group::gdraw()
{
    for(int i = 0; i < o.size(); i++)
    {
         //o -> std::vector<obj> o; in header
        o.at(i).draw();
    }
}

int group::size()
{
     //o -> std::vector<obj> o; in header
    return o.size();
}

std::vector<obj> group::getVector()
{
      //o -> std::vector<obj> o; in header
    return o;
}

//object class

#include "obj.h"
#include <iostream>

using namespace std;

obj::obj()
{

}


//output the values
void obj::draw()
{
    cout << "x is= " << x << endl;
    cout << "y is= " << y << endl;
}


//set the x value of the object
void obj::setX(int x)
{
    this->x = x;
}


//set the y value of the object
void obj::setY(int y)
{
    this->y = y;
}


//return the x value of the object
int obj::getX()
{
    return x;
}


// return the y value of the object
int obj::getY()
{
    return y;
}

[TwilightSpectre]

You need to return your inner vector by reference, otherwise you are just modifying a copy of the vector.

[homing]

true, so u mean like this ?

std::vector<obj> &renderer::getVector()
{
return g.getVector();
}

getting the error

invalid initialization of non-const reference of type 'std::vector<obj>&' from an rvalue of type 'std::vector<obj>'
return g.getVector();
^

tried to fix this but actually have no idea with the const problem

[TwilightSpectre]

You'll need to make them all references. From what I can see of your code, you will need to change to the following things:
- obj& render::getObj
- std::vector<obj>& renderer::getVector
- obj& group::get
- std::vector<obj>& group::getVector

The rvalue error is because you were returning a reference to the temporary copy of the vector returned by the group::getVector function.

[homing]

thanks man.
it's working now :)