What pre knowledge is required before joining btech in cse?

There is no need for nervousness when you are entering in a joyful college life. Whatever knowledge you have about science subjects and mathematic is enough for the first year of B.Tech CSE.

Because engineering maths and engineering science along with basic engineering subjects will be taught during the first 2 semesters of B.Tech. So whatever programming language you learned in your +2 is enough for the first year. Least of all you can revise the algorithm in maths . It will help you in your programming.

Computer Science students have the advantage of knowing the basics of the computer science before the college unlike Mechanical or Civil engineering students. Recollect those basics of school level computer science and if you don't have prior knowledge in computer languages then go and learn some computer languages like Java, C, C++, python from local institutes.

You can also learn C, C++, Java, Python from online you tube videos. Start from C. If you have passion then programming and coding is not a big thing. You will start enjoying it really. Just coding only is not computer science. You should have the knowledge of analyzing and reasoning .

Knowing the subject prior to B.Tech will definitely give you advantage over others.