In C language 1.what is the difference between int main and int main(void) ? 2.why do we use return 0 at the end of the code ?

1. 'int main' defines an integer variable called 'main'. 'int main(void)' defines a function that accepts no parameters and returns an integer.

2. In Unix / Linux / DOS / Windows, the return value from the 'main()' function is traditionally returned as the "exit code" from the program. It is a means of telling the operating system whether the program succeeded. If the program is run in a script / batch file / command file, the script may use this "exit code" to select different actions.

The only three values defined by the C Standard are 0, which traditionally means "success", EXIT_SUCCESS, and EXIT_FAILURE. The last two values are defined in <stdlib.h>