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why return an int from main?
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Posting Whiz in Training
i hope that this does not sound like a silly question but can someone please tell me why we return an integer from the main method in c++?
if program execution starts and ends in main then what is the point? main calls other mothods and receive return types so why does main have to return something itself?
if program execution starts and ends in main then what is the point? main calls other mothods and receive return types so why does main have to return something itself?
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Posting Pro in Training
Last edited by Bench; Jul 18th, 2007 at 7:16 am.
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Historically,
- C++ was derived from C.
- In C, everything was an int unless specified otherwise (there was no void), so it was natural for main to return int.
- C programs were originally developed for command line use, and using a command line interpreter which was far more capable 30 years ago than M$ cmd.exe is even today. That command interpreter could easily determine whether the program just ran was a success (or not) from the value returned by main.
- C++ was derived from C.
- In C, everything was an int unless specified otherwise (there was no void), so it was natural for main to return int.
- C programs were originally developed for command line use, and using a command line interpreter which was far more capable 30 years ago than M$ cmd.exe is even today. That command interpreter could easily determine whether the program just ran was a success (or not) from the value returned by main.
I always learned that main returns an int so that you can put
exit(0), exit(1) and other constructions in to tell you why the program quit. Or would that not work...? Beware of the Rancor. I'm not kidding.
If it doesn't compile, try saying "By the power of MegaMan!!!" <this has kinda worked for me, actually...>
Scotland is NOT North Britain, Glasgow does NOT rhyme with "cow", and Robbie Burns is...well, if you don't already know who he was, you're kinda screwed.
If it doesn't compile, try saying "By the power of MegaMan!!!" <this has kinda worked for me, actually...>
Scotland is NOT North Britain, Glasgow does NOT rhyme with "cow", and Robbie Burns is...well, if you don't already know who he was, you're kinda screwed.
yup. The code is returned to the operating system and can be polled from other programs (like shellscripts) to determine the reason why the program terminated (with 0 traditionally indicating that everything worked smoothly).
As people are clearly allowed to attack me but I'm not allowed to defend myself, I no longer post to this site.
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Originally Posted by venomlash 
I always learned that main returns an int so that you can putexit(0),exit(1)and other constructions in to tell you why the program quit. Or would that not work...?
If i have a void main() and in the code I write exit(11). When I call this program from command line what will be return code of it?
Are you Agile.. ?
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You're still wrong even if your only way out is via exit()
http://c-faq.com/ansi/voidmain3.html
http://c-faq.com/ansi/voidmain3.html
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Some compilers will even let you declare main as returning a pointer! (VC++ 6.0 for example)
But since pointers are really integers the program will actually return the integer value of that pointer. Meaningless -- absolutely. But I've seen someone try to do it.
C++ Syntax (Toggle Plain Text)
But since pointers are really integers the program will actually return the integer value of that pointer. Meaningless -- absolutely. But I've seen someone try to do it.
Don't PM me with questions -- you might get a nasty PM in response. If you have a question then post it in one of the forums.
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Originally Posted by quintoncoert
if program execution starts and ends in main then what is the point? main calls other mothods and receive return types so why does main have to return something itself?
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Originally Posted by Ancient Dragon
Some compilers will even let you declare main as returning a pointer! (VC++ 6.0 for example)
C++ Syntax (Toggle Plain Text)
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