Menu
The ISO 1998 c++ standard specifies that not explicitly using a return statement in the main is equivalent to use return 0. But what if an implementation has a different standard "no error" code, for example -1?
Why not use the standard macro EXIT_SUCCESS that would be replaced either by 0 or -1 or any other value depending on the implementation?
C++ seems to force the semantic of the program, which is not the role of a language which should only describe how the program behaves. Moreover the situation is different for the "error" return value: only EXIT_FAILURE is a standard "error" termination flag, with no explicit value, like "1" for example.
What are the reasons of these choices?
577
The function printf is defined in stdio. h. The next statement, return EXIT_SUCCESS; indicates that when the main function exits, it should return the value EXIT_SUCCESS. The value EXIT_SUCCESS is defined in stdlib.
As the user-defined function declaration mandates return 0, so we must utilize return 0, or return -1 within each C program. If we wouldn't directly declare a value, the assembler automatically includes a return 0; so it is optional to insert a return 0.
C++ return 0 in the main function means that the program executed successfully. return 1 in the main function means that the program does not execute successfully and there is some error.
The default return value from a function is int. Unless explicitly specified the default return value by compiler would be integer value from function.
Returning zero from main() does essentially the same as what you're asking. Returning zero from main() does not have to return zero to the host environment.
From the C90/C99/C++98 standard document:
If the value of status is zero or
EXIT_SUCCESS, an implementation-defined form of the status successful termination is returned.
196
Actually, return 0 won't necessarily return 0! I'm quoting the C standard here, because it's what I know best.
About return in main():
5.1.2.2.3 Program termination
If the return type of the main function is a type compatible with
int, a return from the initial call to themainfunction is equivalent to calling theexitfunction with the value returned by themainfunction as its argument;
About exit():
7.20.4.3 The exit function
Synopsis#include <stdlib.h> void exit(int status);[...]
Finally, control is returned to the host environment. If the value ofstatusis zero orEXIT_SUCCESS, an implementation-defined form of the status successful termination is returned.
28
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
