why do some programs work on some compliers while others dont?

This is a discussion on why do some programs work on some compliers while others dont? within the C++ Programming forums, part of the General Programming Boards category; ok so im using Dev-C++ complier. I just wrote the simpliest program ever yet I cant get it to run. ...

  1. #1
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    why do some programs work on some compliers while others dont?

    ok so im using Dev-C++ complier. I just wrote the simpliest program ever yet I cant get it to run. I complied it and all but dos just pops up really quick and disappears. Here is the code:
    Code:
    #include <iostream>
    using namespace std;
    
    int main() {
        cout << "Never fear C++ is here!";
        return 0;
    }
    why wont this simple program run in this complier? I need to understand why and how to fix it, thanks

  2. #2
    aoeuhtns
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    It does run, but once it finishes, the window closes. Run it from a console window or put something in that takes user input in order to see the results.
    There are 10 types of people in this world, those who cringed when reading the beginning of this sentence and those who salivated to how superior they are for understanding something as simple as binary.

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    is the return 0 code closing it? How do I run it from the console window? I want to understand why this program closes so I wont make this mistake in the future. Thanks

  4. #4
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    put

    Code:
    System ("PAUSE");
    at the end of the file before return 0. This is on the faq.

  5. #5
    Moderately Rabid Decrypt's Avatar
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    Using system() is, in general, not recommended as it opens up some security issues. For little practice and learning programs, it's not a big deal. However, it's better to avoid it now so you don't get into the habit of it later.

    Running your program from the command line is the better option. How to do this depends on your OS. Assuming Windows, go to the Start menu, click run. Type 'cmd' and press enter. Go to the directory the program is in and run in from there. The console window will stay open after the program is completed.
    There is a difference between tedious and difficult.

  6. #6
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    Or use an IDE that keeps it open for you.

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    Or better yet, open your program through the console.

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    I won't start getting into persona preference, but I say live easy now, then worry about what the hardcore do later.

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    so to run it using the cmd commnad I would type what? The program is located in my documents/programs folder/neverfear.cpp

    how would I type that in the dos screen to run it? Thanks alot guys for the help.

  10. #10
    and the hat of wrongness Salem's Avatar
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    cd "Documents\programs"
    myprog.exe

    With suitable replacements for your actual directory and program name.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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  11. #11
    Frequently Quite Prolix dwks's Avatar
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    Quote Originally Posted by indigo0086
    put

    Code:
    System ("PAUSE");
    at the end of the file before return 0. This is on the faq.
    Since C and C++ are case-sensitive, System is different from system. I think you meant system, with a lowercase s.

    [edit] http://faq.cprogramming.com/cgi-bin/...&id=1043284385 [edit]
    dwk

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  12. #12
    Its hard... But im here swgh's Avatar
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    Simply put

    Code:
    cin.get()'
    before return 0
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  13. #13
    Frequently Quite Prolix dwks's Avatar
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    Code:
    cin.get()'
    ->
    Code:
    cin.get();
    of course.

    The FAQ has a more elaborate implementation:
    Code:
    #include <ios>      // Required for streamsize
    #include <iostream>
    #include <istream>
    #include <limits>   // Required for numeric_limits
    
    void myflush ( std::istream& in )
    {
      in.ignore ( std::numeric_limits<std::streamsize>::max(), '\n' );
      in.clear();
    }
    
    void mypause() 
    { 
      std::cout<<"Press [Enter] to continue . . .";
      std::cin.get();
    } 
    
    int main()
    {
      int number;
    
      // Test with an empty stream
      std::cout<<"Hello, world!\n" ;
      mypause();
    
      // Leave extra input in the stream
      std::cout<<"Enter more than one character" ;
    
      myflush ( std::cin );
      mypause();
    
      std::cin.get();
    }
    cin.get() is fine when there's nothing in the input buffer; but if there is, you need to get rid of it.
    dwk

    Seek and ye shall find. quaere et invenies.

    "Simplicity does not precede complexity, but follows it." -- Alan Perlis
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    I'm surprised people brought up system pause but not cin.ignore().

    Try putting cin.ignore(); at the end of your program and that should make the window stay open. Dev-C++ was the first compiler I used to program with. Almost all programs that I wrote in Dev had to have a cin.ignore(); at the end so the programs would not close so fast. I stopped using Dev when I found out that you can download MS visual C++ express and use it for free. With MS visual C++ express you don't have to include pauses to keep the program console window open.


    Hope this helps

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