Thread: get the return value of a program

  1. #1
    Registered User Queatrix's Avatar
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    Post get the return value of a program

    How can I get the return value of a program that I launched from my program?

  2. #2
    Registered User SKeane's Avatar
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    How are you calling the program from within a program?

    popen(), system(), fork()/exec() ?

  3. #3
    and the hat of int overfl Salem's Avatar
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    http://faq.cprogramming.com/cgi-bin/...&id=1043284392
    Which of these are you using to run your sub-program?
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.

  4. #4
    (?<!re)tired Mario F.'s Avatar
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    echo %errorlevel%
    Originally Posted by brewbuck:
    Reimplementing a large system in another language to get a 25% performance boost is nonsense. It would be cheaper to just get a computer which is 25% faster.

  5. #5
    Registered User Queatrix's Avatar
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    CreateProcess().

  6. #6
    and the hat of int overfl Salem's Avatar
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    I dunno, something imaginative like reading the manual page for CreateProcess(), which has a handy "see also" section.
    Obviously, this is the place to look for related functions, and gosh, there it is.
    http://msdn.microsoft.com/library/de...odeprocess.asp
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.

  7. #7
    Registered User Queatrix's Avatar
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    Code:
    BOOL WINAPI GetExitCodeProcess(
      HANDLE hProcess,
      LPDWORD lpExitCode
    );
    Does this mean that
    Code:
    DWORD main()
    is proper and valid too?


    Also, what happens when I try to get the exit code on a
    Code:
    void main()
    program?

    Thanks for link , kinda stupid question thought I suppose, seeing how I have USED THE STUPID FUNC BEFORE! (Seeing the function prototype again brought it back.)
    Last edited by Queatrix; 10-10-2006 at 11:19 AM.

  8. #8
    Frequently Quite Prolix dwks's Avatar
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    Also, what happens when I try to get the exit code on a
    Code:
    void main()
    program?
    Why do you think you're not supposed to use void main()?
    dwk

    Seek and ye shall find. quaere et invenies.

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  9. #9
    Registered User Queatrix's Avatar
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    Yea, that's what I figured, but still, what would happen? Would the function fail? Or would it just return 0x00000000?

  10. #10
    Frequently Quite Prolix dwks's Avatar
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    It's undefined!
    dwk

    Seek and ye shall find. quaere et invenies.

    "Simplicity does not precede complexity, but follows it." -- Alan Perlis
    "Testing can only prove the presence of bugs, not their absence." -- Edsger Dijkstra
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  11. #11
    Its hard... But im here swgh's Avatar
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    True, but a really old compiler like turbo C++ or MSVC++6.0 would accept it as being a valid statement. Nowdays, most people put int main ( void )

  12. #12
    Registered User Queatrix's Avatar
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    Is DWORD main(void) valid too?

  13. #13
    pwns nooblars
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    There is a saying on IRC channels...

    TIAS!

    (Try it and see!)

  14. #14
    Registered User Queatrix's Avatar
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    Quote Originally Posted by Dev-C++
    5 test.cpp `main' must return `int'
    Nope.

    Why is Win32 sooo... hung up on DWORD!?

  15. #15
    and the hat of int overfl Salem's Avatar
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    > DWORD main()
    int main is the portable answer.

    It's just that a DWORD is capable of storing all possible integer values on that particular platform. I guess win32 GUI programs which begin with winmain() also return a DWORD as the exit status.

    Besides, very few operating system shells can cope with process exit status values which exceed 8 bits, it isn't that much of a deal.

    > Also, what happens when I try to get the exit code on a
    <clint>Well punk, do you feel lucky</clint>
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.

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