c++ - Adding static libcurl to Code::Blocks IDE

Question

I can't figure out how to properly add a static libcurl library to my Code::Blocks IDE. I want it static because then no .dll files, which are not included in Windows by default, are needed during runtime of my program. I am using this libcurl: http://curl.haxx.se/dlwiz/?type=lib&os=Win32&flav=- (minGW without OpenSSL)

Here are my global compiler settings: http://img845.imageshack.us/img845/1381/halpr.jpg

I am getting the following error:

ld.exe||cannot find -lCURL_STATICLIB| ||=== Build finished: 1 errors, 0 warnings ===|

when compiling this code:

include <stdio.h>
include <curl/curl.h>

int main(void)
{
CURL *curl;
CURLcode res;

curl = curl_easy_init();
if(curl) {
curl_easy_setopt(curl, CURLOPT_URL, "http://google.com");
res = curl_easy_perform(curl);

/* always cleanup */
curl_easy_cleanup(curl);
}
return 0;
}

Obviously it does not find CURL_STATICLIB, thu I got no idea why. I am not even sure if it was needed to add CURL_STATICLIB to my linker settings(I read it on other forums). I found some guys having same problem, but it isn't properly answered on any place:

stackoverflow.com/questions/4176503/frustrated-with-libcurl

forums.codeblocks.org/index.php?topic=11391.0

old.nabble.com/gcc-working-with-libcurl-td20506927.html

forums.devshed.com/c-programming-42/linker-error-using-libcurl-698071.html

I am so tired of fighting with this, please help me.

EDIT:

Hello Victor, thank you for response!

I will try to be as detailed as possible, so there are no missunderstandings. So, here is the image of the directory/folder tree for my C:libs folder:

http://img199.imageshack.us/img199/6977/curl1.png

As you can see, it also includes build log, you will notice that the error this time is different than the one I posted previously. It's because I changed global compiler and build project settings.

My new Build Project settings: http://img863.imageshack.us/img863/4404/buildoptions.png My new Global Compiler settings: http://img225.imageshack.us/img225/4926/curl2.png

I am sure I have configured these settings wrong and that's why I can not compile it.

Answer 1

Okay, I managed to build your example successfully with libcurl using static linkage. The details involved to make this work are quite intricate -- setting it up correctly can get tricky for the unwary.

Here are the steps I used to make this work, be sure to follow them carefully:

1. Go to Project build options->Compiler settings->#defines: type in CURL_STATICLIB. When this is defined the libcurl.h header will have its function signatures preprocessed to fit static linkage. Otherwise dynamic linkage is assumed and the mangled names then become _imp__*. The unresolved errors from your screenshot indicate it's attempting a dynamic link rather than the desired static link.
   

2. Under Project build options->Linker settings->Link libraries make sure it contains the following: curl, rtmp, idn, ssl, ssh2, crypto, z, ws2_32, wldap32, winmm, gdi32. Note that order is important. Due to a design deficiency of the gnu linker, the most dependant libraries need to be listed first followed by least dependant. Other linkers like msvc link and borland's ilinker do not exhibit such issues -- the libraries can be listed in any order.

3. Under Project build options->Linker settings->Other linker options add in '-static'. This will make sure that the static version of 'idn' is used. If this switch is omitted then your compiled program could depend on 'libidn-11.dll' to run which probably isn't what you want.
   

At this point, you should be able to compile and link libcurl programs without any issues. A couple things worth mentioning,

• Under Other linker options the other extra switches from your screenshot aren't needed. 'libcurl.a' is already listed and covered by Link libraries.

• The 'libcrypto.a' seems to cover the same references as the 'libeay32.a' so only one of them is needed. However, 'libeay32.a' causes dynamic linkage despite its larger size. If you want your application to be 'fully self-contained' use 'libcrypto.a' instead like in the screenshot.

• If you wish to link dynamically in the future, just replace the listing with 'curldll' under Link libraries and remove the CURL_STATICLIB define. The extra libraries (eg. ssl, idn, rtmp etc.) aren't needed since libcurl.dll already covers them.

• You can avoid the tedious error prone setup of a new libcurl program by employing codeblocks' user templates. (eg. File->New->Project->User templates)

Hopefully this resolves any build problems you have with libcurl once and for all.