How do I link libcurl to my c++ program in linux?

Question

I need to use libcurl in a piece of software I am writing on my ubuntu machine. I am using Eclipse to write and compile all of the software. When I put the libcurl files in the same folder as the .cpp file, and include the curl.h file in the header, When I attempt to compile the program, It comes up with these errors:

Building target: sms Invoking: GCC C++ Linker g++  -o"sms"  ./src/sms.o    ./src/sms.o: In function `main': /home/geekman/workspace/sms/Debug/../src/sms.cpp:38: undefined reference to `curl_easy_init' /home/geekman/workspace/sms/Debug/../src/sms.cpp:42: undefined reference to `curl_easy_setopt' /home/geekman/workspace/sms/Debug/../src/sms.cpp:44: undefined reference to `curl_easy_setopt' /home/geekman/workspace/sms/Debug/../src/sms.cpp:46: undefined reference to `curl_easy_perform' /home/geekman/workspace/sms/Debug/../src/sms.cpp:47: undefined reference to `curl_easy_cleanup' collect2: ld returned 1 exit status make: *** [sms] Error 1 

I took the contents of the include folder from libcurl, and placed them in the same folder as the .cpp file. then in the header of the .cpp file, I typed:

#include <curl/curl.h> 

I also tried:

#include "curl/curl.h" 

Any ideas on the problem? Thanks.

Answer 1

Your header file inclusions are just fine; your problem is occurring at the linking step. In order to link against libcurl, you need to add the -lcurl command line option, assuming it's installed in a standard directory:

g++ -o sms ./src/sms.o -lcurl 

If it's not installed in a standard directory, you also need to add the -L/path/to/libcurl, e.g. something like:

# Assuming that /home/geekman/workspace/libcurl is where libcurl.a is located g++ -o sms ./src/sms.o -L/home/geekman/workspace/libcurl -lcurl 

Also note that the -lcurl option has to appear after the list of object files you're linking, otherwise it won't link properly.

Answer 2

You can try to use curl-config --libs.