Example - Hello World¶

Objective¶

This example creates, compiles, and runs a C Hello World program and demonstrates that the development kit includes a primitive development system and can run user-created applications.

Prerequisites¶

• Basic knowledge of the "vi" editor.
  • Or the ability to copy-and-paste

    The vi provided in the Development Kit is a BusyBox version of vi and is very limited in order to be tiny. Many commands and options are not implemented.

Steps¶

• Create the hello.c source file.
  • Using vi
    • Start vi. (enter vi hello.c)
    • Enter insert mode: press the i key
    • Enter the following text. (or copy and paste)
      

      #include <stdio.h>
      
      int main ()
      {
          printf ("Hello World!!\n");
      }
      

    • Exit insert mode: press the escape key (esc)
    • Save the file: enter :w
    • Exit the editor: enter :q
  • Using cat
    

    cat <<EOF >hello.c
    #include <stdio.h>
    
    void main()
    {
        printf ("Hello World!!\n");
    }
    EOF
    

• Compile and link the program
  

  gcc -c hello.c
  gcc hello.o -o hello
  

• Run the program
  

  ./hello
  

  
  This produces the following output:
  

  Hello World!!
  

• The complete session:
  

  root@mitysom-am57x:~# cat <<EOF >hello.c
  > #include <stdio.h>
  >
  > void main()
  > {
  >     printf ("Hello World!!\n");
  > }
  > EOF
  root@mitysom-am57x:~# gcc -c hello.c
  root@mitysom-am57x:~# gcc hello.o -o hello
  root@mitysom-am57x:~# ./hello
  Hello World!!
  root@mitysom-am57x:~# 
  

Conclusion¶

In this example you have created, compiled, and run a C Hello World program and demonstrated that the development kit includes a basic development system and can run user-created applications.