Programming for an embedded app

Is there one or two locations that can show me how to write a program from scratch.

From scratch, in a nutshell .....

If you used Visual Studio C/C++ already, then you do not need a lesson in the C/C++ languages themselves.  For C/C++ programming, you'll need to get used to employing two basic tools:

1. a GUI source code editor
2. the gcc Compiler

For #1, I prefer the `gedit` tool; for #2, I use the `gcc` tool.  Get them like this:

     sudo apt-get install gedit gcc

Another good tool for C/C++ development is `make`.  If `which make` doesn't show you that you already have it, then do this:

     sudo apt-get install make

The `make` utility, while quirky, allows you to automate compiling and perform maintenance tasks related to source code, libraries, and executables.  Actually, a "Makefile" can specify almost anything that you'd like.

A simplistic example:

• Establish a source repository.  E.g. I have one being a folder called "src" under my home directory.
• Under $HOME/src, create a folder called "hello".
• Open a terminal window and execute:

     cd $HOME/src/hello

     gedit hello.c

• Enter the following lines, save, and then exit from gedit:

     #include <stdio.h>

     int main ( int argc, char **argv ) {

          printf ( "Howdy, y\'all\n" );

          return 0;

     }

• Still in $HOME/src/hello, execute:

     gcc -o hello hello.c

• Execute the compiled program:

     hello

Some C/C++/gdb/make tutorials:

http://www3.ntu.edu.sg/home/ehchua/programming/cpp/gcc_make.html

http://pages.cs.wisc.edu/~beechung/ref/gcc-intro.html

http://cseweb.ucsd.edu/classes/fa09/cse141/tutorial_gcc_gdb.html

How do I get a display to work with gedit? I get an error "could not open X display".  I don't know what the possible values for X in "gedit --display=X" are.

What OS did you install?  Most folks use Raspbian (Raspberry Pi flavor of Debian) or a flavor of Ubuntu.  I mentioned that above.

See https://www.raspberrypi.org/downloads/

Raspian

Wrote this program as suggested above.

#include <stdio.h>

     int main ( int argc, char **argv ) {

          printf ( "Howdy, y\'all\n" );

          return 0;

     }

• Still in $HOME/src/hello, execute:

     gcc -o hello hello.c

• Execute the compiled program:

     hello

>> I just wanted to see that I could make it work. I don't recall having so many problems when I was using QNX many years ago but it won't execute. I get no errors and see hello in the directory as an executable (ls -l) but I get an error "hello: command not found". I changed the output file name to "test" and run it - I get no error but get no output. I know I am doing something stupid but I can't figure it out. I would have though there were some libraries somewhere that I would have to link to.

./hello is correct way to execute if you are in the current directory for hello

C

Thanks VERY much.

Thanks VERY much.