Thread: Learning C++ by Example

I didn't find out how to.
My idea is create a track object and then gettracks. then iterate, but doesn't allow me, because tracks doesn't have the getTracks()

Code:

    auto tracks = MyCds.GetTracks;
//    for (unsigned i = 0; i < tracks.size(); ++i) {
//        std::cout << tracks.at(i).GetTrackName() << std::endl;
//    }

Update Code:

Code:

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



class XTrackInfo
{
    std::string m_TrackName;
    int m_Length;

public:
    XTrackInfo() {}

    XTrackInfo(std::string TrackName, int Length):
        m_TrackName(std::move(TrackName)),
        m_Length(Length)
    {}

    void SetTrackName(std::string TrackName) { m_TrackName = std::move(TrackName); }
    void SetTrackLength(int Length) { m_Length = Length; }

    const std::string& GetTrackName() const { return m_TrackName; }
    int GetTrackLength() const { return m_Length; }
};

class XMusicCd
{
private:
    // You may not modify these member variables
    std::string m_Author;
    std::vector<XTrackInfo> m_TrackInfo;

public:
    // You may not modify these member functions


    XMusicCd() {}
    XMusicCd(std::string Author, std::vector<XTrackInfo> Tracks):
        m_Author(std::move(Author)),
        m_TrackInfo(std::move(Tracks))
    {}

    void SetAuthor(std::string Author) { m_Author = std::move(Author); }

    const std::string& GetAuthor() const { return m_Author; }
    const std::vector<XTrackInfo>& GetTracks() const { return m_TrackInfo;}


    void AddTrack(XTrackInfo NewTrack){

        m_TrackInfo.emplace_back(std::move(NewTrack));

    }

    int GetLenght() const{

        int sum=0;

        auto && MyTracks = this->GetTracks();

        for (auto && elem : MyTracks)
        {
            sum+= elem.GetTrackLength();

        }

    return sum;
    }




};

class XCollection
{
    private:


    std::vector <XMusicCd> m_cdCollection;

    public:
    XCollection(){}
    XCollection(std::vector <XMusicCd> CdCollection):
    m_cdCollection(std::move(CdCollection))
    {}


    const std::vector <XMusicCd>& GetCds() const {return m_cdCollection;}

    void addCD(XMusicCd NewCD){

        m_cdCollection.emplace_back(std::move(NewCD));

   }




};

//void CalcTotalLen(const XMusicCd& Cd){
//    int sum = 0;
//    auto && MyTracks = Cd.GetTracks();

//    for (auto && elem : MyTracks)
//    {
//        sum+= elem.GetTrackLength();

//    }
//    std::cout << "total len: "<< sum << std::endl;

//}

void PrintCollectionContents(const XCollection& Collection){
    //std::cout << "Cd number : " << "1" << "\n";
    std::cout << "Cd info : " << std::endl;

    auto MyCds = Collection.GetCds();

    for(auto && elem: MyCds){
        std::cout << elem.GetAuthor() << std::endl;

        //How can I acess the tracks of the particular cd ?
    }
    auto tracks = MyCds.GetTracks;
//    for (unsigned i = 0; i < tracks.size(); ++i) {
//        std::cout << tracks.at(i).GetTrackName() << std::endl;
//    }


}

void PrintCdContents(const XMusicCd& Cd)
{
    std::cout << "Author : " << Cd.GetAuthor() << "\n";
    std::cout << "\n" << std::endl;
    std::cout << "Track Info" << std::endl;


    //std::vector<XTrackInfo> tracks = Cd.GetTracks();
     auto && MyTracks = Cd.GetTracks();

//    for (std::vector<XTrackInfo>::const_iterator it = tracks.begin(); it != tracks.end(); ++it) {
//        std::cout << it->GetTrackName() << std::endl;
//        std::cout << it-> GetTrackLength() << std::endl;
//    }

//     std::vector<XTrackInfo> tracks = Cd.GetTracks();
//     for (unsigned i = 0; i < tracks.size(); ++i) {
//         std::cout << tracks.at(i).GetTrackName() << std::endl;
//     }
     for (auto && elem : MyTracks)
     {
             std::cout << elem.GetTrackName() << std::endl;
             std::cout << elem.GetTrackLength() << std::endl;
     }


}

int main()
{
    // You may not change this function
    XMusicCd MyCd;
    MyCd.SetAuthor("Hello World");
    MyCd.AddTrack(XTrackInfo("This is a test", 100));
    MyCd.AddTrack(XTrackInfo("This is a test 2", 200));
    PrintCdContents(MyCd);
    //CalcTotalLen(MyCd);
    std::cout << "total cd lenght: " << MyCd.GetLenght()<< std::endl;

    XMusicCd MyCd2;
    MyCd2.SetAuthor("Hello World 2");
    MyCd2.AddTrack(XTrackInfo("This is a test", 400));
    MyCd2.AddTrack(XTrackInfo("This is a test 2", 500));
    PrintCdContents(MyCd2);
    //CalcTotalLen(MyCd);
    std::cout << "total cd lenght: " << MyCd2.GetLenght()<< std::endl;

    XCollection MyCollection;
    MyCollection.addCD(MyCd);
    MyCollection.addCD(MyCd2);
    //MyCollection.size();
    PrintCollectionContents(MyCollection);

}

What's with all the "You may not change this ..." comments?

Originally Posted by antred

What's with all the "You may not change this ..." comments?

Elysa's initial instructions.

Originally Posted by marcoesteves

Elysa's initial instructions.

Ah, ok. Sorry, didn't read through the entire thread (it's rather long).

Originally Posted by antred

Ah, ok. Sorry, didn't read through the entire thread (it's rather long).

no Problem

Ok, it is fine, I think that I'm too attached at i 's and j's .

Now, I'm thinking: "Ok print them all it's fine, but I want to acess a particular index? My class types doesn't have "at" implemented. It is possible using iterators?

It's time to go to the deeper example, or just test more functionalities at this one?


Updated code:

Code:

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


class XTrackInfo
{
    std::string m_TrackName;
    int m_Length;

public:
    XTrackInfo() {}

    XTrackInfo(std::string TrackName, int Length):
        m_TrackName(std::move(TrackName)),
        m_Length(Length)
    {}

    void SetTrackName(std::string TrackName) { m_TrackName = std::move(TrackName); }
    void SetTrackLength(int Length) { m_Length = Length; }

    const std::string& GetTrackName() const { return m_TrackName; }
    int GetTrackLength() const { return m_Length; }
};

class XMusicCd
{
private:

    std::string m_Author;
    std::vector<XTrackInfo> m_TrackInfo;

public:

    XMusicCd() {}
    XMusicCd(std::string Author, std::vector<XTrackInfo> Tracks):
        m_Author(std::move(Author)),
        m_TrackInfo(std::move(Tracks))
    {}

    void SetAuthor(std::string Author) { m_Author = std::move(Author); }

    const std::string& GetAuthor() const { return m_Author; }
    const std::vector<XTrackInfo>& GetTracks() const { return m_TrackInfo;}


    void AddTrack(XTrackInfo NewTrack){

        m_TrackInfo.emplace_back(std::move(NewTrack));

    }

    int GetLenght() const{

        int sum=0;

        auto && MyTracks = this->GetTracks();

        for (auto && elem : MyTracks)
        {
            sum+= elem.GetTrackLength();

        }

    return sum;
    }

};

class XCollection
{
    private:


    std::vector <XMusicCd> m_cdCollection;

    public:
    XCollection(){}
    XCollection(std::vector <XMusicCd> CdCollection):
    m_cdCollection(std::move(CdCollection))
    {}


    const std::vector <XMusicCd>& GetCds() const {return m_cdCollection;}

    void addCD(XMusicCd NewCD){

        m_cdCollection.emplace_back(std::move(NewCD));

   }

};


void PrintCollectionContents(const XCollection& Collection){


    std::cout << "Cd info : " << std::endl;

    for (auto && Cd : Collection.GetCds()){ // ...for every cd...
        std::cout << Cd.GetAuthor() << std::endl;

        for (auto && Track : Cd.GetTracks()) // ... for every track...
            std::cout << Track.GetTrackName() << std::endl;
    }

}

void PrintCdContents(const XMusicCd& Cd)
{
    std::cout << "Author : " << Cd.GetAuthor() << "\n";
    std::cout << "\n" << std::endl;
    std::cout << "Track Info" << std::endl;

     auto && MyTracks = Cd.GetTracks();

     for (auto && elem : MyTracks)
     {
             std::cout << elem.GetTrackName() << std::endl;
             std::cout << elem.GetTrackLength() << std::endl;
     }


}

int main()
{
    // You may not change this function
    XMusicCd MyCd;
    MyCd.SetAuthor("Hello World");
    MyCd.AddTrack(XTrackInfo("This is a test", 100));
    MyCd.AddTrack(XTrackInfo("This is a test 2", 200));
    PrintCdContents(MyCd);
    //CalcTotalLen(MyCd);
    std::cout << "total cd lenght: " << MyCd.GetLenght()<< std::endl;

    XMusicCd MyCd2;
    MyCd2.SetAuthor("Hello World 2");
    MyCd2.AddTrack(XTrackInfo("This is a test  3", 400));
    MyCd2.AddTrack(XTrackInfo("This is a test  4", 500));
    PrintCdContents(MyCd2);

    std::cout << "total cd lenght: " << MyCd2.GetLenght()<< std::endl;

    XCollection MyCollection;
    MyCollection.addCD(MyCd);
    MyCollection.addCD(MyCd2);
    PrintCollectionContents(MyCollection);

}

Originally Posted by Elysia

Code:

std::vector<int> v;
// Now create code that accesses the n'th element of v.

struct X { std::vector<int> v; };
X x;
// Now create code that accesses the "n'th element" of x.

I don't know if I'm doing something wrong when I create the project.

I think the 1st part is done, the second one not, something is missing.

Code:

#include <iostream>
#include <vector>

std::vector<int> v;
// Now create code that accesses the n'th element of v.


struct X { std::vector<int> v; };

// Now create code that accesses the "n'th element" of x.

int main()

{
    X x;

    for (int i=1; i<10; i++) v.push_back(i);   // 1 2 3 4 5 6 7 8 9


     std::cout << "myvector contains:";
     for (std::vector<int>::iterator it=v.begin(); it!=v.end(); ++it)
       std::cout << ' ' << *it;
     std::cout << '\n';

     std::cout << "myvector contains:";

     for (std::vector<int>::iterator it=x.v.begin(); it!=x.v.end(); ++it)
       std::cout << ' ' << *it;

     std::cout << '\n';

    return 0;
}

Here it is another update. I hope that is what you ask for Elysia:

Code:

#include <iostream>
#include <vector>

std::vector<int> v;
// Now create code that accesses the n'th element of v.


struct X { std::vector<int> v; };

X x;

// Now create code that accesses the "n'th element" of x.

int main()

{
     for (int i=1; i<10; i++) v.push_back(i);   // 1 2 3 4 5 6 7 8 9


     std::cout << "myvector contains:";
     for (std::vector<int>::iterator it=v.begin(); it!=v.end(); ++it)
       std::cout << ' ' << *it;
     std::cout << '\n';

     //Struct

     x.v.resize(2);
     x.v[0] =1;
     x.v[1] = 2;


     std::cout << "myvector in struct contains:";
     for (std::vector<int>::iterator it=x.v.begin(); it!=x.v.end(); ++it)
       std::cout << ' ' << *it;
     std::cout << '\n';

    return 0;
}

Originally Posted by Elysia

Does this exercise answer your question?
"Now, I'm thinking: "Ok print them all it's fine, but I want to acess a particular index? My class types doesn't have "at" implemented. It is possible using iterators?"

Iterators come with magic xD

Should I apply to the more complex example all of this Stuff?

I've updated a git : https://github.com/CreativeSoftware/LearnCppByExample

How can I can I make a book price change according to the label color?

I was thiking about user interface. Probably is a good practice the user interface be independent of all code.
In other words, to the current classes it must doesn't matter if it is a window or a prompt from Console. Should I create another class naming Interface?

Book's price it is a function of labelcolor.
So, it seems to me correct price be a private attribute without setfunction (to the user), however with a mutator function to the program.

When a user sets a label color changes the price.