Why do advance compilers need return values and old compilers didn't?

Question

old compilers for c++ used to compile and run programs without returning values then why do we now need main function to return value? what was the error that we used to get so as we needed to add return values as compulsory part of main function syntax too?

Answer 1

Main is an int function. Int functions have to return values. Some new compilers will add a return 0; if you forget. Most do not. Main can technically be void and not return a value, but it doesn't make much sense. You have to handle exceptions and errors in C++, and without return codes, you'll be doing a lot of searching through good code, breaking things trying to find bugs.

tl;dr return statements are used mainly for errors/successes