Hey Arbar,

Honestly Speaking there is nothing that you definitely need to know before joining CSE. The programming taught at school level in India is such that you can catch up with others, well most of them, with just 10-15 days of practice. Also first years do not have a complete CSE specific course and all subjects are taught here so there may be only one or two programming related courses in first year.

However If you have zero or little knowledge of programming i would suggest you learn Basics of C and C++ programming from a beginner level book like Let Us C by Yashwant Kanetkar to get up to the level of most of the class.

All the best!