Compiling with libcurl

[halfpower]

I'm trying to compile a program using libcurl. I installed libcurl3, but I'm not sure if this is the right package. I'm have this in my code:

#include <curl/curl.h>
but I get a lot of error messages such as

getpage.c:16: error: ‘CURL’ undeclared (first use in this function)
when I try to compile. Is the some compiler flag that I need to have on the command line when I compile?

[johnl]

Hi,

You need to install libcurl3-dev or libcurl4-dev to get the header files associated with the library.

When compiling, you should pass $(pkg-config --cflags libcurl) to gcc. When linking, $(pkg-config --libs libcurl). If you are compiling and linking in one step you can do it like so:

gcc myfile.c $(pkg-config --libs --cflags libcurl) -o myprogram

Hope this helps.

[CannedCorn]

This works:



gcc myfile.c $(pkg-config --libs --cflags libcurl) -o myprogram


But this would be easier to understand maybe?



gcc myfile.c -lcurl -o myprogram


Maybe someone could describe how they are different?

[stevebu56]

This works:



gcc myfile.c $(pkg-config --libs --cflags libcurl) -o myprogram


But this would be easier to understand maybe?



gcc myfile.c -lcurl -o myprogram


Maybe someone could describe how they are different?

Yes, that would be easier to understand but it hard codes the location of the curl library. It has to be in /usr/lib or /usr/local/lib since those are the default directories where gcc searches (http://www.network-theory.co.uk/docs/gccintro/gccintro_21.html) for libraries. What if I build the curl library from source and drop it in my home directory? This is the problem that the pkg-config program alleviates. When I build and install curl a pkg-config (http://pkg-config.freedesktop.org/wiki/) file is built based on where I installed curl then any other program can reference that file in order to include the headers or link to the libraries.

Hope this clarifies things a little.