No-one said anything about the variables coming from user input. Please explain, while you're happy to add random points to a thread, why the code you quoted is not safe.

sandhyagupta, whether you know it or not, your post was very vague and we really have nothing to go on with regards to understanding your problem and therefore nothing for us to help you with. Please come back and add some more detail to let us know exactly what you're wanting to do.