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Thread: A little problem in compiling C code

  1. #1
    Join Date
    Jan 2013
    Beans
    4

    Unhappy A little problem in compiling C code

    Hello Everyone!!
    I am new here and this is my first post. I am running Ubuntu 12.04 on my desktop and I am facing a problem compiling my C code (which works perfectly on my Windows Laptop). I tried Hello World program to test it out-
    Code:
    #include<stdio.h>
    #include<conio.h>
    void main()
    {
    clrscr();
    printf("Hello World!!");
    getch();
    }
    Then, I try compiling this code using the following command from terminal-
    Code:
    gcc -o Output Hello.c
    where (as is obvious), I stored the file with the name Hello.c .
    I get the following error (copied as is from the terminal)-
    Code:
    Hello.c:2:18: fatal error: conio.h: No such file or directory
    compilation terminated.
    It gives the same error when I try-
    Code:
    g++ -o Output Hello.c
    Since this is the simplest of the C programs I have seen, I'm not sure why either of the 2 compilers is not able to work with conio.h . I looked it up in my help file on my Windows laptop and it said that the conio.h header file was not compatible with Unix even when it was compatible with DOS. So, is this the reason I'm not able to compile the code? If yes, then please suggest me some header files which are-
    1. Compatible only with GNU/Linux
    2. Platform independent
    which I can use instead of conio.h and yet get the full functionality of it.
    conio.h is the most used header file in C/C++ (more than stdio.h and iostream.h and I haven't seen one of my programs written without it). So even if the header file must change, it must be able to provide the entire functionality of conio.h . I actually didn't expect this when I switched to Linux (which I hear is created entirely in C but I may be wrong). This is a bit of a disappointment for me...

  2. #2
    Join Date
    Jun 2007
    Location
    Malvern, UK
    Beans
    992
    Distro
    Ubuntu 10.04 Lucid Lynx

    Re: A little problem in compiling C code

    Welcome.
    http://stackoverflow.com/questions/6...e-or-directory

    Have a google first with the compiler message.

  3. #3
    Join Date
    May 2008
    Location
    UK
    Beans
    1,448
    Distro
    Ubuntu 8.04 Hardy Heron

    Re: A little problem in compiling C code

    Quote Originally Posted by vishurockssrivastava View Post
    Hello Everyone!!
    I am new here and this is my first post. I am running Ubuntu 12.04 on my desktop and I am facing a problem compiling my C code (which works perfectly on my Windows Laptop). I tried Hello World program to test it out-
    Code:
    #include<stdio.h>
    #include<conio.h>
    void main()
    {
    clrscr();
    printf("Hello World!!");
    getch();
    }
    Then, I try compiling this code using the following command from terminal-
    Code:
    gcc -o Output Hello.c
    where (as is obvious), I stored the file with the name Hello.c .
    I get the following error (copied as is from the terminal)-
    Code:
    Hello.c:2:18: fatal error: conio.h: No such file or directory
    compilation terminated.
    It gives the same error when I try-
    Code:
    g++ -o Output Hello.c
    Since this is the simplest of the C programs I have seen, I'm not sure why either of the 2 compilers is not able to work with conio.h . I looked it up in my help file on my Windows laptop and it said that the conio.h header file was not compatible with Unix even when it was compatible with DOS. So, is this the reason I'm not able to compile the code? If yes, then please suggest me some header files which are-
    1. Compatible only with GNU/Linux
    2. Platform independent
    which I can use instead of conio.h and yet get the full functionality of it.
    conio.h is the most used header file in C/C++ (more than stdio.h and iostream.h and I haven't seen one of my programs written without it). So even if the header file must change, it must be able to provide the entire functionality of conio.h . I actually didn't expect this when I switched to Linux (which I hear is created entirely in C but I may be wrong). This is a bit of a disappointment for me...
    Conio is a windows only functionality and getch is a windows only call - you will need to write your own version of getch - if you really need it.

    As i understand it - getch here is used to keep the terminal open once you run the program in windows - windows executables will automatically open a terminal for you if you double click on a program which needs a terminal. If you don't use getch on windows, then the terminal closes immediately and you wont see the output.

    On Linux, a terminal is not automatically opened for you, so if you open a terminal to run your code - which you will need to do, then you don't need getch (or anything like it) since the terminal stays open.

    The first thing you need to is get away from the thought that WIndows and Linux will behave the same way - they wont - they are different OSes - conio and getch are just one example where Windows has added generally non-standard functionality.
    Tony - Happy to try to help.
    Unless otherwise stated - all code posted by me is untested. Remember to Mark the Thread as Solved.
    Ubuntu user number # 24044 Projects : TimeWarp - on the fly Backups

  4. #4
    Join Date
    Sep 2012
    Location
    UK
    Beans
    Hidden!
    Distro
    Ubuntu 12.04 Precise Pangolin

    Re: A little problem in compiling C code

    There are some windows only bits to your code. However with slight modification this works
    Code:
    #include<stdio.h>
    
    void main()
    {
      printf("Hello World!!");
      getchar();
    }
    it compiles with

    gcc -o Output Hello.c

    However, the C standard defines that main must return an int. g++ complains and won't compile it.

    so
    Code:
    #include<stdio.h>
    
    int main()
    {
      printf("Hello World!!");
      getchar();
      return 0;
    }
    Is better and compiles with both

    gcc -o Output Hello.c

    and

    g++ -o Output Hello.c

  5. #5
    Join Date
    Nov 2005
    Location
    Bordeaux, France
    Beans
    11,297
    Distro
    Ubuntu 12.04 Precise Pangolin

    Re: A little problem in compiling C code

    However, the C standard defines that main must return an int. g++ complains and won't compile it.
    I don't see how that's relevant, since g++ compiles C++, not C. Also, in C99 main() implicitly returns 0 if no explicit return statmeent is present.
    「明後日の夕方には帰ってるからね。」


  6. #6

    Re: A little problem in compiling C code

    Quote Originally Posted by Bachstelze View Post
    Also, in C99 main() implicitly returns 0 if no explicit return statmeent is present.
    But is still not permitted to be void, on a hosted implementation.

  7. #7
    Join Date
    Apr 2011
    Location
    Texas
    Beans
    73
    Distro
    Ubuntu 10.04 Lucid Lynx

    Re: A little problem in compiling C code

    Code:
    #include <stdio.h>
    #include <termios.h>
    #include <unistd.h>
    
    int mygetch( ) {
      struct termios oldt,
                     newt;
      int            ch;
      tcgetattr( STDIN_FILENO, &oldt );
      newt = oldt;
      newt.c_lflag &= ~( ICANON | ECHO );
      tcsetattr( STDIN_FILENO, TCSANOW, &newt );
      ch = getchar();
      tcsetattr( STDIN_FILENO, TCSANOW, &oldt );
      return ch;
    }
    This should give you the same functionality of getch from windows.

    I don't expect you to know what's going on which is fine, but feel free to copy and paste the code.
    Last edited by Ghostmn; January 20th, 2013 at 07:54 PM.

  8. #8
    Join Date
    Apr 2008
    Location
    Cleveland, OH
    Beans
    10
    Distro
    Hardy Heron (Ubuntu Development)

    Re: A little problem in compiling C code

    Sorry guys; but I have a C# ASP.NET question.

    Unfortunately, I have to deal with C# - and so, my question is about developing Winform applications in MonoDevelop.

    I have been to other threads dealing with Mono Winforms - such as:

    1. http://ubuntuforums.org/showthread.p...t=winform+mono (I've tried to install sudo apt-get mono-winforms - as the thread suggests; but I have encountered problems similar to those in item #2 listed below.

    2. http://ubuntuforums.org/archive/index.php/t-468183.html

    3. http://ubuntuforums.org/showthread.p...t=winform+mono

    Regretfully, I am asking this question because of a class at school. I don't want to bash Msft; but, I have gotten use to actually controlling my own computer through Linux Ubuntu. It seems as though I may have to deal with Northwind Traders(lol) after all.

    Any help you can provide would be greatly appreciated. I can't use Gtk or any other programming options; Microsoft is my prom date.

    Thank you in advance for you consideration...

  9. #9
    Join Date
    Jan 2013
    Beans
    3

    Re: Problem compiling a simple .c code

    Hello forum,
    I am an absolute beginner in ubuntu 12.04 LTS. I have two problems which are as follows:

    01.

    I am having problem getting the output of a C code. I wrote the code in gedit and saved it as hello.c on desktop. The code is as follows:

    Code:
    #include<stdio.h>
    void main()
    {
        printf("Hello world\n");
    }
    In order to run and compile the hello.c file, I wrote
    Code:
    gcc hello.c
    and got "a.out" file on desktop but I don't see any output "Hello world". I want to see the "Hello world" output. So, help me on how I can see that "Hello world" output and also how to run a.out file or what to do with a.out file.


    02.

    I read some of the posts and I saw that the instruction to open a terminal is
    Application>Accessories>Terminal
    But I can't find the "Application". If anybody can help me to locate the Application tab or folder or icon will be appreciated.

    P:S: I do know how to open a terminal window but only using the shortcut ctrl+Alt+T But I want to learn the other ways to do so.

    Apologies if I made any mistake regarding the post or anything. Thanks.
    Last edited by gbsmailadd; January 22nd, 2013 at 08:13 AM.

  10. #10
    Join Date
    Sep 2012
    Location
    UK
    Beans
    Hidden!
    Distro
    Ubuntu 12.04 Precise Pangolin

    Re: Problem compiling a simple .c code

    1. Application>Accessories>Terminal

    is the old way to get a terminal, It still works if you use the "Gnone Classic" desktop but if you are using Unity you don't have it any more. You can search for it in the Dash or press CTRL, ALT and T together to get the terminal

    2. a.out is the default output file name. If you want it to be called something else you have to tell it what. Your command should have been

    gcc -o HelloWorld Hello.c

    then to run it enter

    ./HelloWorld

    In a terminal once you are in the correct directory.

    ------
    Alternativley if you are happy for the program to be called "a.out"

    ./a.out

    should run it
    Last edited by Warren Hill; January 22nd, 2013 at 01:20 PM.

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