This question already has an answer here:
I develop a small website now some of my friends asking to give us the code.so i want now to do a trick in my code that no one can copy or modify my code.if any one know's please post.
</div>
Copy: Forget it. If you give the code to someone, he can just copy and re-use it. Consider using an appropriate license for your code to make shure the receiver knows what he is allowed to do with your code
Changes: Use a version control system. As a developer you must learn to use at least one. Do it now. I recommend git, but there are plenty of VCS`ses available (svn,bazaar,cvs...)