Use libcurl undefined reference to 'curl_easy_init'

Question

use libcurl to writer some test code. when try to compile, it says undefined reference. already use -lcurl or -L compile option.

root@ubuntu:~/work/test/curlTest# curl-config --libs
-L/usr/lib/x86_64-linux-gnu -lcurl
root@ubuntu:~/work/test/curlTest# gcc -L/usr/lib/x86_64-linux-gnu -lcurl curl.c -o curl
/tmp/ccnFnpaW.o: In function `main':
curl.c:(.text+0xb1): undefined reference to `curl_global_init'
curl.c:(.text+0xbc): undefined reference to `curl_easy_init'
curl.c:(.text+0x109): undefined reference to `curl_easy_setopt'
curl.c:(.text+0x136): undefined reference to `curl_easy_setopt'
curl.c:(.text+0x145): undefined reference to `curl_easy_perform'
collect2: error: ld returned 1 exit status

Merriweather

already tried, same result – Merriweather

Answer 1

-lcurl should be put in the end of gcc command.

gcc -L/usr/lib/x86_64-linux-gnu curl.c -o curl -lcurl

Overkill

For me it was enough to simply move the -l option to the end of the command – Huda

Great, it worked for me. But I still don't know why the position of -lcurl matters. Why it failed before -o but work fine after -o? – Impetus

It is because gcc linking is order-sensitive and that your linked libraries must follow the things that depend on. – Shipshape