Hello,

No, it is not necessary to study in Computer Science in Class 11th and 12th to become an Computer Science Engineer. The minimum education qualification requirement for admission to Computer Science Engineering is 10+2 or its equivalent. You must have studied Mathematics, Physics and Chemistry from a recognized board in 10+2 level. This is the basic requirement. Depending on the institute you wish to join you need to score the minimum percentage of marks in the qualifying examination. Here is the list of entrance examination for admission to Engineering

https://engineering.careers360.com/exams

You can check the eligibility criteria by clicking on the name of the exam.