C++ Arrays: Electronic Billboard Imitation

[inihility]

Let me state first off that this is not a school assignment, its something I thought that would be nice to do and well I ended up with the idea of using arrays to perform the task (if possible).

I've done a cast-based animation with a static int, and bool, which works, however is limited to one line (prove me wrong, I'm still new to this).

This is what I have so far, in terms of the function that animates the 'billboard':

void animateBoard()
{
    //for (int x = 0; x < 20; x++)
    //{
 
    for (int i = 0; i < 20; i++)
    {
        for (int j = 0; j < 20; j++)
        {
            for (int k = 0; k < 20; k++)
            {
                myArray[k][i] = myDisplay[k][19-i];
                //myArray[19-k][j-19-i] = '_';
            }
            for (int l = 0; l < 20; l++)
            {
                myArray[l][i-j] = myDisplay[l][19-i];
            }
            displayBoard();
            Sleep(250);
            system("cls");
        }
 
    /*
    int x, y, i, j;
    y = 19;
    for (i = 0; i < 20; i++)
    {
        x = 19;
        for (j = 0; j < 20; j++)
        {
            myArray[j][i] = myDisplay[x][y];
            x--;
        }
        y--;
        Sleep(250);
        system("cls");
        displayBoard();
 
        //for (x = 0; x <= i; x++)
        //{
        //    for (y = 0; y <= j; y++)
        //    {
        //        myArray[y][x] = '_';
        //    }
            //Sleep(220);
            //system("cls");
            //displayBoard();
        //}
    }
    */
 
    }
}

I have two, two-dimensional arrays, and I am using a recursion function (several nested) to change their values.

As you can see I've tried a lot of methods that I have commented out and most just deleted (the current version does something bizzarre). The problem I am having is that its not giving me any error instead it doesn't print the desired results. I've had it do what I wanted (in a sense) diagonally, however printing in a non-chronological order.

I'm trying to imitate a common advertising electronic billboard you see everywhere that shuffles a message (or picture) across the screen or perform some sort of animation.

I'm quite confident its possible to do this in C++ while it may be tedious, I hope someone can help me out here.

Thanks.

[inihility]

I forgot to add that in the code provided, it is based on the already mentioned two, two dimensional arrays of the size 20 (thus the i < 20, etc. conditions).

[weaknessforcats]

When you cast in C++, you destroy the type safety of your program. Casting in C++ is used when a) you are calling a relic C function with a void* argument or b) your C++ design is screwed up.

The code I see here is C code.

Then there's this:

I'm trying to imitate a common advertising electronic billboard you see everywhere that shuffles a message (or picture) across the screen or perform some sort of animation.

This looks like a base class ElectronicBillboard Crawler data member.

class ElectronicBillboard
{
   private:
      Crawler   c;
};
 

The Crawler is a base class with a virtual Crawl() method. So you derive a CrawlingPicture class from Crawler and override the Crawl() method. CrawlingPicture IS-A Crawler.

The ElectronicBillboard has a Display() method and part of that method is to display the crawler.

void ElectronicBillboard::Display()
{
      //displays the main board here
     while(etc...)
     {
      this->c->Crawl()//displays the crawler
     }
}
 

You create CrawlingPicture object and use it as a Crawler object.

CrawlingPicture cp("c:\\thepicture.jpg");
ElectronicBillboard b("the text of the top of the board", cp);
b.Display();          //shows the text of the billboard with the picture crawling across the bottom.
 

You just add derived classes from Crawl for the various crawlers.

[inihility]

Thanks for the reply weaknessforcats. Could you perhaps put together a small example of a 3(?) line message/characters running across the screen? I'm pretty new to C++ (at the really beginning of OOP) like I mentioned earlier and I'm having a little trouble trying to understand all the code snippets, what they do, and where they should be put, so it would be really helpful if you could use the Crawler (class?) in an example, that way I could probably analyse the example and have a better understanding of how things work.

Also when I mentioned cast-based animation, I mean't that I did it before to clear things up, and not in this example as I was only able to animate one line at a time at most (I'm trying to simultaneously animate several lines).

Many thanks.

[weaknessforcats]

Here you go:

#include <windows.h>
#include <iostream>
using namespace std;
#include <string>
 
class Crawler
{
   public:
     virtual ostream& Crawl(ostream& os) = 0;
};
 
class TextCrawler : public Crawler
{
   private:
    string text;
  public:
    TextCrawler(string str);
    ostream& Crawl(ostream& os);
 
 
};
TextCrawler::TextCrawler(string str)
: text(str)
{
 
}
ostream& TextCrawler::Crawl(ostream& os)
{
   string spaces;
   for (int i = 0; i < 3; ++i)
   {
     for (int i = 0; 60 > spaces.size(); ++i)
     {
        os << '\r' << spaces << text;
        spaces += "      ";
        Sleep(500);
     }
     spaces += "                 ";
     os << '\r' << spaces;
     spaces.erase();
     }
     return os;
}
class ElectronicBillBoard
{
    private:
      Crawler* c;
      string str;     //the billboard text
    public:
      ElectronicBillBoard(string text, Crawler* thecrawler);
      //Display the billboard:
      friend ostream& operator<<(ostream& os, const ElectronicBillBoard& bb);
};
ElectronicBillBoard::ElectronicBillBoard(string text, Crawler* thecrawler)
: str(text), c(thecrawler)
{
}
ostream& operator<<(ostream& os, const ElectronicBillBoard& bb)
{
        string str("                               ");
        os << str << bb.str << endl << endl << endl;
        bb.c->Crawl(os);
        return os;
}
 
int main()
{       Crawler* crawler = new TextCrawler("Buy today");
        ElectronicBillBoard   billboard("Used cars cheap", crawler);
 
        cout << billboard << endl;        
}