exit(-3)

Hi,

What exit(-3) means. Also, I want to know the difference between it and exit(0), exit(1),exit(-2)

Thanks

I've only seen two uses of exit() in source code.
> exit(0);
This is to terminate the program with successful results. This means that the operating system won't bother you about the program crashing or terminating in an unusual way. You should consider using the EXIT_SUCCESS macro instead.

> exit(EXIT_FAILURE);
This terminates the program, but the OS will prompt you about the program crashing or terminating in an unusual way. Using numbers in place of the macro is probably fine, but I don't think you should. It's a magic number.

From the diff man page

Code:

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  An exit status of 0 means no differences were found, 1 means some
differences were found, and 2 means trouble.

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The only portable return values are
0 - meaning success
EXIT_SUCCESS - meaning success
EXIT_FAILURE - meaning failure

Anything else depends on how your environment interprets the parameter.

FWIW, I would stick to small positive integers for indicating varying degrees of success back to the environment.

1 is also portable (for falure).
Actually, any non zero Value should be interpreted as a falure.

Unless you actually use the return value in a script. Then it is meaningfull to have other return values.

Quote:

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1 is also portable (for falure).
Actually, any non zero Value should be interpreted as a falure.

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Are you sure? C99 doesnt seem to state what the values of EXIT_SUCCESS and EXIT_FAILURE should be, except that it is implied that EXIT_FAILURE cannot be 0. Although it would be rather inane to do it that way, it seems that EXIT_SUCCESS does not have to be 0.

From section 7.20.4.3:

Quote:

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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.

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> 1 is also portable (for falure).
You've obviously never programmed for a VAX then.
1 is success in that part of the world.

Not that it matters to your well-written programs which return 0, since the run-time takes care to map that to the implementation "success".

Quote:

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Originally Posted by Salem

> 1 is also portable (for falure).
You've obviously never programmed for a VAX then.
1 is success in that part of the world.

Not that it matters to your well-written programs which return 0, since the run-time takes care to map that to the implementation "success".

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Darn, Salem, you beat me to it.

I cut my "C teeth" on VAXen, and when I switched to Unix (well, DEC's Ultrix at that time) it felt strange to look for 0 for success and 1 for failure.

I believe it stayed the same for VMS on Alpha, but lost track of how C progressed in that world shortly thereafter.....