Why we use return =0 in the end ?

Question

Is there any specification? Is it mandatory?

Answer 1

This is status code which means that the code executed successfully.

Answer 2

the return statement is used to terminate a function. The main function should return value 0, it means EXIT_SUCCESS, and otherwise returns -1, meaning EXIT_FAILIURE

Answer 3

It is not really mendatory
If even if you dont put return 0, still code will execute sucesfully unless you dont make any error in the code.