I hope you came looking for how do people make “computer viruses” (because making human viruses is a different topic)
Ok let me tell you first, this post is not a tutorial on how to code a virus straight away, but just to give you an idea how do the people, who make viruses, make one.
How do people make a virus
1. By mistake
Obviously, not the needed answer, but thats one of the way they get a virus too. Most of the time some errors in code, instead of making it fail, make it act as a virus
2. By copy pasting codes
This is what most of people online are doing. Just going online and searching for some code, copying it, making a virus and then teasing and damaging their friends.
3. By coding themselves
Any programmer, who know a programming language, and knows how computer or servers work, can make a virus. This is the real way to make viruses (or worms and trojans).
So in short, if you want to code a virus (which you shouldn’t want anyway) first learn a programming language and you won’t be asking this question again. Sometimes because you will know how to code a virus, and sometimes, because you will no longer wish to know how to make a virus anymore.