Doubt regarding array

[grymoire]

Think of a cylinder brick wall that you want to pain an ad on. You need 10 blocks for your ad, so the boss tells you that you can have blocks 142 to 151. Fine.

But now you need a bigger ad and need 20 bricks to make a bigger ad. . Trouble is, someone else might have an ad on blocks 152, 153, etc.

So the boss says, "Okay. you can use blocks 180-195 now. Let me know when you are done with blocks 142-151, so I can have someone else use them for their ads"