How to run C++ program using GCC?

Question

I need to run a demo program, ba_demo.cpp, which is in a folder structure, "C:/root/demo_parent1/demo_parent2/demo.cpp", and this file uses the following code in it.

#include "root/sub1/sub2/header_file.h".

The file is at

'C:/root/sub1/sub2/header_file.h'

When I try to compile the demo program by the command

C:\root\demo_parent1\demo_parent2> gcc demo.cpp

it is not finding the header file and is throwing an error. What changes should I make to my command in order to run the demo program successfully?

First off, you aren't executing anything with `gcc demo.cpp`, that would compile it (creating an executable program). Then you'd need to run it. That said, do you have a file `header_file.h` in `c:\root\demo_parent1\demo_parent2\root\sub\sub2\`? — nerdwaller, Jul 01 '14 at 22:39
@nerdwaller yes..i do have a header_file.h..but in C:/root/sub1/sub2 — User1234321232, Jul 01 '14 at 22:40
You could try using the -I flag to gcc to specify the path to look for header files on. Also, since this is a C++ program you probably want to use g++ rather than gcc. — Lucas Holt, Jul 01 '14 at 22:43

score 3 · Answer 1 · answered Jul 01 '14 at 22:46

First you must inform your compiler where to look for root directory by adding flag -IC: so your command will look like this:

C:\root\demo_parent1\demo_parent2> g++ demo.cpp -IC:

But that's not practical. Better change include to

#include header_file.h

and add only /root/sub1/sub2/ directory, which will look like this:

C:\root\demo_parent1\demo_parent2> g++ demo.cpp -IC:\root\sub1\sub2\

Now you have your program compiled to a.out file. You execute it by

C:\root\demo_parent1\demo_parent2>./a.out

You can change output name to demo.exe like this:

C:\root\demo_parent1\demo_parent2> g++ demo.cpp -IC:\root\sub1\sub2\ -o demo.exe

Please note that since you work on Windows under some &nix simulator the slashes in my examples might be wrong but I can't check them now. Use google to check how to handle them properly.

EDIT: Also, don't forget to take Lukas Holt's advice and use g++! It is very important to use proper compiler for proper language.

If the slashes are a problem, usually syntax like this works /c/root/sub1/sub2/ in cygwin bash shells and things. — Lucas Holt, Jul 01 '14 at 22:48
I have never worked under Cygwin, and last time I worked under MinGW I had slahes totally mixed up and everything worked anyway. — Darth Hunterix, Jul 01 '14 at 22:50

score 1 · Answer 2 · edited Feb 04 '16 at 19:46

Your .cpp file is in: C:/root/demo_parent1/demo_parent2/demo.cpp

You include:

#include "root/sub1/sub2/header_file.h"

This is a relative path. You need either to specify an include directory with the -I flag, or to move header_file.h to C:/root/demo_parent1/demo_parent2/root/sub1/sub2/header_file.h. The most simple solution would be to just #include "header_file.h" and to move it into the same directory as demo.cpp.

Then you will be able to compile it with gcc, and to execute the generated file.

How to run C++ program using GCC?

2 Answers2