Compiling in c: include file not found - c

I got following error
'libwebsockets.h' file not found
but I have installed libwebsockets with the command
brew install libwebsockets
How can I solve this error?
I want to implement a websocketserver and i need this.
If my code is only has this following line
#include <libwebsockets.h>
it gave me an error.
I tried to compile it with gcc foo.c

You need to pass the appropriate compile and link flags to the compiler for it to find the headers and libraries.
This is usually done with the program "pkg-config". To get the compile flags, run:
pkg-config libwebsockets --cflags
To get the link flags:
pkg-config libwebsockets --libs
If you compile and link in the same step, you need to pass the flags that are output by both of the above commands to the compiler. If you have separate compilation and link commands, you pass the "--cflags" output during compiling, and the "--libs" output during linking.
In your case, you can compile with:
gcc $(pkg-config libwebsockets --cflags) foo.c $(pkg-config libwebsockets --libs)
The $() syntax takes the output of the command you put between ( and ) and puts it into yours, as if you had typed it in.
You should probably write a small build script to do that for you. For example in a file named "build" in the same directory as "foo.c":
#! /bin/sh
gcc $(pkg-config libwebsockets --cflags) foo.c $(pkg-config libwebsockets --libs)
Make the script executable:
chmod +x build
And then just call it:
./build

Related

Compile hiredis in C on Mac OS X

I'm trying to compile a client using hiredis in C on Mac OS X.
I've installed hiredis with:
brew install hiredis
But still get the error:
fatal error: 'hiredis.h' file not found
My hiredis.h is however in:
/usr/local/include/hiredis/hiredis.c
How do I tell the compiler this?
I'm compiling with:
gcc test.c -o test
In your question you said hiredis.h is in /usr/local/include/hiredis/hiredis.c, which doesn't really make any sense.
Assuming you meant that your hiredis.h is in /usr/local/include/hiredis. You can do like:
gcc test.c -I/usr/local/include/hiredis -o test
Read about -I in this SO post.
UPDATE:
As mentioned by #EricPostpischil in comments, its a better idea to just include like:
#include < hiredis/hiredis.h>
I am still not sure if /usr/local/include is in default include path. If it is, well no need to do anything, just compile like:
gcc test.c -o test
and if it isn't,
gcc test.c -I/usr/local/include -o test
If you have installed hiredis with homebrew, you can see what's in the package like this:
brew ls --verbose hiredis
/usr/local/Cellar/hiredis/0.14.0/INSTALL_RECEIPT.json
/usr/local/Cellar/hiredis/0.14.0/CHANGELOG.md
/usr/local/Cellar/hiredis/0.14.0/.brew/hiredis.rb
...
...
/usr/local/Cellar/hiredis/0.14.0/lib/libhiredis.dylib
/usr/local/Cellar/hiredis/0.14.0/lib/pkgconfig/hiredis.pc <--- PKG-CONFIG
/usr/local/Cellar/hiredis/0.14.0/lib/libhiredis.a
/usr/local/Cellar/hiredis/0.14.0/lib/libhiredis.0.14.dylib
...
...
And, as you can see, it gives you a pkg-config file with all the settings in it that you need. So, you might as well install pkg-config and do it properly!
brew install pkg-config
Now, if you want to know the C compiler flags for hiredis, you do:
pkg-config --cflags hiredis
-D_FILE_OFFSET_BITS=64 -I/usr/local/Cellar/hiredis/0.14.0/include/hiredis
And if you want to know the linker settings, you do:
pkg-config --libs hiredis
-L/usr/local/Cellar/hiredis/0.14.0/lib -lhiredis
And so, your compile-link command becomes very simple and updates itself when you update the packages:
gcc-9 $(pkg-config --cflags --libs hiredis) -o program program.c

GTK2.0 is installed but unable to locate when compiling

I am brand new to GTK and looking to compile my first program with it. Upon compiling I get the following error:
randall#randall-ubuntu:~/c_programs/bettingCalc$ gcc -o bettingCalc main.c
main.c:8:21: fatal error: gtk/gtk.h: No such file or directory
#include <gtk/gtk.h>
^
compilation terminated.
The typical solution seems to be running the command:
sudo apt-get install libgtk2.0-dev
Which I ran, and seemingly successfully installed. What am I missing here?
if it is at all relevant, here is the last 8 lines of the installation process:
Setting up libxcomposite-dev (1:0.4.4-1) ...
Setting up x11proto-damage-dev (1:1.2.1-2) ...
Setting up libxdamage-dev:amd64 (1:1.1.4-1ubuntu1) ...
Setting up libxml2-utils (2.9.1+dfsg1-3ubuntu4.4) ...
Setting up libgtk2.0-dev (2.24.23-0ubuntu1.1) ...
Setting up libsys-hostname-long-perl (1.4-3) ...
Setting up libmail-sendmail-perl (0.79.16-1) ...
Processing triggers for libc-bin (2.19-0ubuntu6.4) ...
randall#randall-ubuntu:~/c_programs/bettingCalc$
You have to use gtk-config in compile/link cycle to get info about installed GTK
http://manpages.ubuntu.com/manpages/intrepid/man1/gtk-config.1.html
UPDATE: gtk-config is depreciated, please use pkg-config to achieve desired result and get right
includes, flags and library references
For compilation
gcc -c main.c `pkg-config --cflags gtk+-2.0`
For linking
gcc -o app main.o `pkg-config --libs gtk+-2.0`

Cannot compile a simple c-program using gtk-lib

I am trying to implement a graphic userinterface to my c-programs. To that i have installed the GTK3.0-pacakge to my computer and followed the tutorial. But I am not able to compile a simple c-program that shows a 200*200 px window.
According to the tutorial one should compile like this:
gcc base.c -o base ‘pkg-config --cflags --libs gtk+-3.0‘
Where base.c is the actual program and pkg-config is the program in the bin-folder that tells the compiler where to find the header-files and libraries.
If I just test if the pkg-config-file is there I write its name in the cmd-window:
pkg-config
I get the following answer:
Must specify package names on the command line
So I actually have this config-file.
But when I try to compile base.c with the above syntax that is
gcc base.c -o base pkg-config --cflags --libs gtk+-3.0
I get the following errors
gcc: error: pkg-config: No such file or directory
gcc: error: unrecognized command line option '--clfags'
gcc: error: unrecognized command line option '--libs'
gcc: error: gtk+-3.0: no such file or directory
So why do I get these compilation errors?
Have I missunderstood what is shown in the tutorial? Is the compilation syntax just an abbreviation of what one should do?
You've just wrongly understood the tutorial. In you string disappeared the back ticks which are vital.
That means, the right line is
gcc base.c -o base `pkg-config --cflags --libs gtk+-3.0`
Compare to your (wrong) line:
gcc base.c -o base pkg-config --cflags --libs gtk+-3.0
All the staff starting with pkg-config is an independent command, not a flag for gcc.
Back ticks tell the shell to run its contents in a subshell and substantiate the result of the command run in the gcc command line.

glib.h and gtk.h not found

Hi everyone I have a program with the following includes:
gtk/gtk.h
glib.h
I have used the commands:
sudo apt-get install libgtk2.0-dev glib
sudo apt-get install glade
But I am still getting the error that glib was not found and gtk/gtk.h was not found. It's the first time I am using gtk and I have no idea how it works or how to install it.
The command you're supposed to use (in more recent releases of linux/gtk) is pkg-config, not gtk-config. gtk-config is intended for pre 2.0 gtk development.
Consider the file you're compiling is called foo.c, to compile it under gtk-2.0, you would use, from the command line the command:
gcc `pkg-config --cflags glib-2.0 gtk+-2.0` foo.c -o foo `pkg-config --libs glib-2.0 gtk+-2.0`
This should compile, and give you a file foo, that can be executed.
but really, use a makefile, as this stuff is a pain to keep typing. I would write out a sample makefile, but there are rules that need to be followed in the formatting of them that makes it difficult to type in the editor window.
# Sample Makefile
CFLAGS := $(shell pkg-config --cflags glib-2.0 gtk+-2.0)
LDFLAGS := $(shell pkg-config --libs glib-2.0 gtk+-2.0)
foo: foo.c
<TAB HERE NOT SPACES>$(CC) $(CFLAGS) $< -o $# $(LDFLAGS)
This defines a simple rule saying to make foo, it depends on foo.c, so of foo.c is newer than foo, it will be rebuilt. Where I write 'TAB HERE NOT SPACES' it must be a tab character, and cannot be a set of space characters.
type "locate glib.h" to determine file's location (assuming a contemporary linux distribution - your post doesn't provide much information).
Then ensure the path to glib.h is properly specified in your Makefile. (You do have a Makefile, don't you?) Perform the same steps for gtk.h.
Please read the official documentation. It explains how to compile GTK applications.
Basically to compile a hello.c file to generate a hello program, you'll type:
gcc `pkg-config --cflags --libs gtk+-2.0` hello.c -o hello

Why can't I build a "hello world" for glib?

So here's the world's simplest glib program:
#include <glib.h>
I try to compile it with gcc test.c and I get:
test.c:1:18: error: glib.h: No such file or directory
So I make sure that I have the right packages:
# dpkg -l | grep libglib
ii libglib-perl 1:1.183-1 Perl interface to the GLib and GObject libra
ii libglib1.2-dev 1.2.10-19build1 The GLib library of C routines (development)
ii libglib1.2ldbl 1.2.10-19build1 The GLib library of C routines
ii libglib2.0-0 2.20.1-0ubuntu2 The GLib library of C routines
ii libglib2.0-cil 2.12.1-1ubuntu2 CLI binding for the GLib utility library 2.1
ii libglib2.0-data 2.18.2-0ubuntu2 Common files for GLib library
ii libglib2.0-dev 2.20.1-0ubuntu2 Development files for the GLib library
ii libglibmm-2.4-1c2a 2.18.1-1 C++ wrapper for the GLib toolkit (shared lib
Then I search for any "glib.h" anywhere under /usr/include. I get two, /usr/include/glib-1.2/glib.h and /usr/include/glib-2.0/glib.h. So I try:
$ gcc -I/usr/include/glib-2.0 -Wall test.c
In file included from /usr/include/glib-2.0/glib/galloca.h:34,
from /usr/include/glib-2.0/glib.h:32,
from test.c:2:
/usr/include/glib-2.0/glib/gtypes.h:34:24: error: glibconfig.h: No such file or directory
(about 10,000 more errors snipped)
I don't seem to have a glibconfig.h anywhere on my computer.
What do I do now?
glib tends to hide itself... Your include statement doesn't work because GCC doesn't automatically search subdirectories, and so cannot see the glib.h in glib-1.2 or glib-2.0.
Read the Compiling GLib Applications page in the GLIB manuals... you use commands like pkg-config --cflags glib-2.0 to get the right flags for GCC.
The canonical way to do what you are trying is
% gcc test.c -Wall -o test `pkg-config --cflags --libs glib-2.0`
Note the back-ticks, which tell the shell to run the pkg-config command "in-place".
> > The canonical way to do what you are trying is
> % gcc test.c -Wall -o test `pkg-config --cflags --libs glib-2.0`
Sorry, but no. That is a common misconception, that just happens to work in most cases on ELF-based systems, Linux in particular. The canonical way is to pass in the cflags and libraries separately, in the correct and traditional locations on the command line, like this:
gcc -Wall -o test `pkg-config --cflags glib-2.0` test.c `pkg-config --libs glib-2.0`
It is a pity that pkg-config accepts both the --cflags and --libs options at the same time, as it means this incorrect meme will never die, and people used to it on Linux will continue to be baffled when they then try the same on other platforms.
As #chris said use pkg-config.
glibconfig.h is missing
it’s because this file is not in the /usr/include/glib-2.0, but in /usr/lib/glib-2.0. So you have to include also this /usr/lib path or copy the file to the /include/glib-2.0
I am using glib.h as well-
Do this to compile all your glib.h programs :)
gcc `pkg-config --cflags --libs glib-2.0` filename.c
Make sure to surround pkg-config --cflags --libs glib-2.0 with back-quotes
which you find under tilde (left most key on the querty keyboard).
Thank me later .. :P
apt-get build-dep is your friend -- nobody can remember all the packages you need to build something.

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