What is return 0 ?

Answer 1

Assuming you mean return 0 from the main, return 0 is just a way that the main knows when to end a program. If a return 0 is initiated from the main, then the program will stop.

Answer 2

In my Opinion return 0. simply tells the compiler that the program has run successful without any errors.

Answer 3

Return 0; shows the end of program and it tells the compiler the program has written succesfuly

Answer 4

Would return SUCCESS make more sense?