Erase the previous line of text

Objective:  To move the text around the window.

We must erase the text before moving it. 

Otherwise, we will see yellow text smeared across the screen.

Listing 3 erases the current line of text in preparation for re-drawing it in the same or in a different location.

Listing 3. Erase the previous line of text.
    //Draw black text on the existing text to erase it.
             screen,//Specify bitmap on the screen
             font,//Use a default font
             "HELLO WORLD",//Specify the text to display
             x,//x-coordinate for text
             y,//y-coordinate for text
             makecol(0,0,0),//Color text black
             -1 );//Transparent text background.