main() functions return value?

Question

Anyone please tell me where the main() function of the 'C' language returns its value?

Answer 1

From the C99 Standard:

5.1.2.2.3 Program termination

1 If the return type of the main function is a type compatible with int, a return from the initial call to the main function is equivalent to calling the exit function with the value returned by the main function as its argument;

and then

7.20.4.3 The exit function

5 Finally, control is returned to the host environment. If the value of status is zero or EXIT_SUCCESS, an implementation-defined form of the status successful termination is returned. If the value of status is EXIT_FAILURE, an implementation-defined form of the status unsuccessful termination is returned. Otherwise the status returned is implementation-defined.

In short, the return value of main is returned to the host environment in an implementation-defined form.

Answer 2

A general statement is: Function returns a value to the host environment.

So main() will return value to any program or shell which is hosting that piece of code or to the OS.

return value 0 is considered as successful execution

Answer 3

C's main function returns an int... that int goes to the program which executed it (the parent process, if you will) as an exit status code.

Specifically, on most operating systems, a 0 exit code signifies a normal run (no real errors), and non-zero means there was a problem and the program had to exit abnormally.

Answer 4

The main function is at libery to return its value at any point at which it pleases. You simply write:

return my_return_value;

and it's game over.

Answer 5

The return value if the main() function is used as the exit status code of the program.

In a shell you can get the exit status of a program using $?, example:

./prog
exit_status=$?