Question

So, I know some Python but I thought that I should try to add some c++ to that knowledge. This is the code I’ve written that I’m playing with (it’s actually a rewrite of some python code). It adds some song data to a class (or a multidimensional array inside a class). So far so good. Most of it work. But I’m stuck at the delSong method. I don’t think I could implement this with arrays, so It’s seems like I’m at a dead end. I read a little about vectors, but they won’t let med delete an item in the middle. How could I get further? Shall I abandon arrays for something else? But what would that be?

#include <iostream>
#include <string>

using namespace std;

class Jukebox{
public:
  void addSong(string artist, string title, string filename) {
    songs [songsCounter][0] = artist;
    songs [songsCounter][1] = title;
    songs [songsCounter][2] = filename;
    songsCounter++;
  }

  void printSong (int song) {
    cout << songs[song][0] << " - ";
    cout << songs[song][1] << " : ";
    cout << songs[song][2] << endl;
  }

  void printSongs () {
    int song;
    for (song=0; song<songsCounter; song++ ) {
      cout << songs[song][0] << " - ";
      cout << songs[song][1] << " : ";
      cout << songs[song][2] << endl;
    }
  }

  void delSong(int song) {
    // Some code here
  }

private:
  int songsCounter;
  string songs [512][3];
};

int main() {
  Jukebox jbox;
  jbox.addSong("U2", "Magnificent", "U2-Magnificent.mp3");
  jbox.addSong("Sting", "Englishman in New York", "Sting-Englishman_in_New_York.mp3");
  jbox.addSong("U2", "One", "U2-One.mp3");
  jbox.printSongs();
  return 0;
}

In my python code I actually using an in memory sqlite3 db. But I could as well write it with a simple list of tuples. And that is a similar approach to what I’m trying to do here. But an in memory sqlite database would also be a possible way for me to do this in c++. But it does’nt look very easy either to implement?

One more thing, I also want to add a sort method later so please have that in mind when you suggest a solution so I don’t get to another dead end… 🙂

Answer 1

Vectors do allow deletion in the middle (look for the erase function), albeit not at the greatest speed.

I’d recomend using a vector of structures instead of a multidimensional array.

struct song {
    string artist;
    string title;
    string filename;
};

And then in your Jukebox:

vector<song> songs;

The vector grows as needed and keeps track of its own size, contrary to the array.

For sorting, there’s std::sort function in the <algorithm> header.