Cool Computer Science Concepts Part ~ 1

In computer science, there are a lot of cool concepts. Some that are interesting, mind-bending, and even some that resemble life itself. The basic building blocks of all life are cells. And cells contain DNA, which has the ability to self-replicate. Can a program do that? Well, what if I ask you to make a program that does exactly that? Replicate itself. So in order to do this, you need something more clever. Somewhere in here, there's a term for this kind of program that can print its exact self. And it's called a quine. Here is a simple example of one in Python. So how does this work? Well, let's start off with the second line where we try to print S percent S. Which means print S, and then when Python reaches this placeholder value inside S, denoted by a percent symbol, it fills it with S itself, including the quotes. And after the print finishes, we are left with this. And the program and the output are exactly identical. Which means this is a quine. And you might be thinking, why does this even matter? And what is significant there? In a program printing itself? Well, imagine you change the quine. So instead of printing the source program, it wrote itself into another file. This is now a self-replicating program. Where if you run program.py, it creates a clone.py with the exact same code. Now imagine, instead of writing a random copy of itself into another file, it looked for a specific target file, someone else's Python file, or files, and inserted a copy of itself. Now we went from a simple program printing itself to the replication mechanisms behind early file-infecting viruses. And of course, modern malware is far more advanced than this, but strip away all the sophistication and answering the exact same question: How does a copy & essentially reproduce itself?