I have a C project with multiple include directories that hold header files with same names but different content. So how can I know which one is included to my main program.
IDE - Eclipse
Compiler - IAR for MSP430
Build - Makefiles
If your includes use the <[file.h]> form, it depends on the include search path of your preprocessor. For gcc, any -I option will append a path to the include search path. The first matching file is used, so the order of -I options matters.
Related
I developed small c application in linux. For this application i placed .h file in
linux standard path (/usr/include). Again i am compiling the same program
Output:
FATA ERROR : xyz.h(my own header file) not found
Do i need to update any variable in gcc or way to solve this problem
Thank You
Place the header file in the same directory as your .c file and use -I. when compiling
gcc -I. main.c -o myprog
You shouldn't place your header files in /usr/include that is meant for the system headers.
Note: you don't actually need the -I. because the current directory is searched by default, nevertheless, it doesn't hurt to add it.
Files specified by include directives are meant to be located in one of the search paths of the complier which are specified with the -I option in many cases (at least for gcc, is it the same for other compilers?). The search paths are verified in the order of definition in the command line.
There are 2 kinds of include directives:
double quoted ones (#include "xyz.h")
angle bracket ones (#include <xyz.h>)
IIRC, the default and first search path for the former is the working directory. For the later, it's compiler dependant, but it's usually /usr/include/.
Depending of the include directive you used, you should pick the right location for your file. Or better, put your file in a good location (say the same place as the including file), and add a search path to your gcc command.
You should separate your header .h files, from system and repository built headers so you don't break anything.
I would recommend making a folder in your home directory called include and just adding it to your path, that way you never have to worry about it again and no need for the -I/flag
I wanted to include a file say a.h in my program which is located at some location say (/ws/uname/bd/lib) & that file in turn has different include statements whose files are located in vastly different locations.
How can i do that by just including the file with "/ws/uname/bd/lib/a.h".
I dont want to change any of the header file.
Appreciate your help
What compiler are you using? If it's clang or gcc, you can use the -I flag to add search paths for header files. From the gcc(1) man page:
-Idir
Add the directory dir to the head of the list of directories to be searched for header files. This can be used to override a system header file, substituting your own version, since these directories are searched before the system header file directories. However, you should not use this option to add directories that contain vendor-supplied system header files (use -isystem for that). If you use more than one -I option, the directories are scanned in left-to-right order; the standard system directories come after.
I have added some source (header files) in a common folder (..\shared\abc) and my code file from another folder (..\src\xyz) has #include <abc/../foo.hpp>. I get this error:
Cannot open Source file error
I can fix that by giving absolute path but that change needs to be done at many place. What should I see to fix this?
Using VC9 nmake to compile code. This is a Makefile based project.
If the included files are from some library your code is using, you'll want to specify the include path with a compiler option. For the Visual C++ compiler the command-line option to specify additional include directories is /I, e.g.:
cl /I ..\shared foo.cpp
You'll need to modify the compiler options in your Makefile accordingly.
I'm trying to use a non-standard header file (http://ndevilla.free.fr/gnuplot). Its used in lots of codes in various different places on my computer. Currently I have to put the header file and the object file in every folder which its needed with the preprocessor directive:
#include "gnuplot_i.h"
In the file. Is there a way by which I can put the header file in one place so I can reference it like other standard header file. Cheers.
Compile with -I<directory>
E.g.
compile with -I/usr/local/gnuplot/inc.
Also it might be worth your reading up on include paths and the difference between:
#include <include_file.h>
and
#include "include_file.h"
Linking in an object file needs to be done explicitly the same way as a C file, which means (I believe) that you need a full path. However if you archive it into a proper library then you can use -l<library name> and -L<library path> instead. E.g.
gcc -I/usr/local/gnuplot/inc -L/usr/local/gnuplot/lib -lgnuplot -o my_prog my_prog.c
Most compilers have a flag -I that lets you add a directory of your choosing to the search path for include files.
I have a set of C files that I would like to use. Can I just copy them to my include directory, or do I have to compile them. I would think they would be compiled in the final binary.
You need to compile those C files if you want to use them.
To make use of what's in those C files, you'll nead a header file that declares what's inside them.
Those header files is what you'd put in your include folder, and you'll compile the C files together with your other C files. (Or you could make a library out of those C files)
Yes, they need to be compiled so that they are available at the linking step. C is not an interpreted language, so having the sources present in an include directory would do nothing for execution.
You can keep the source files at the same location. The include files will be in the include directory. You can use the compilation option -I./<include-file-directory> to specify from where to fetch the include files.
The final binary will be compiled version of all your source files which you give to the compiler. You have to explicitly specify every file to be compiled along the with final executable name.
In case you dont do so a default executable is created with the name a.out(i am assuming the platform to be linux and compiler to be gcc) in the directory where you compile.
Check the link for more details on compilation using Makefile.