When I compile my PHP program it's easily get compiled, but when I run that code it gives me an Error: Could not find or load main class Data?

[Saif]

Hello, I would like to ask you a question about my studies, and my future job. when i compile my php program it's easily get compiled, but when i run that code it gives me an error: could not find or load main class data? Thank you kindly give me an answer please!