undefined reference to curl_global_init, curl_easy_init and other function(C)
CCurlLibcurlC Problem Overview
I am trying to use Curl in C.
I visited Curl official page, and copied sample source code.
below is the link: http://curl.haxx.se/libcurl/c/sepheaders.html
when I run this code with command "gcc test.c",
the console shows message like below.
/tmp/cc1vsivQ.o: In function `main':
test.c:(.text+0xe1): undefined reference to `curl_global_init'
test.c:(.text+0xe6): undefined reference to `curl_easy_init'
test.c:(.text+0x10c): undefined reference to `curl_easy_setopt'
test.c:(.text+0x12e): undefined reference to `curl_easy_setopt'
test.c:(.text+0x150): undefined reference to `curl_easy_setopt'
test.c:(.text+0x17e): undefined reference to `curl_easy_cleanup'
test.c:(.text+0x1b3): undefined reference to `curl_easy_cleanup'
test.c:(.text+0x1db): undefined reference to `curl_easy_setopt'
test.c:(.text+0x1e7): undefined reference to `curl_easy_perform'
test.c:(.text+0x1ff): undefined reference to `curl_easy_cleanup'
I do not know how to solve this.
C Solutions
Solution 1 - C
You don't link with the library.
When using an external library you must link with it:
$ gcc test.c -lcurl
The last option tells GCC to link (-l) with the library curl.
Solution 2 - C
In addition to Joachim Pileborg's answer, it is useful to remember that gcc/g++ linking is sensitive to order and that your linked libraries must follow the things that depend upon them.
$ gcc -lcurl test.c
will fail, missing the same symbols as before. I mention this because I came to this page for forgetting this fact.
Solution 3 - C
I have the same problem, but i use g++ with a make file. This is a linker issue. You need to add option -lcurl on the compiler and on the linker. In my case on the make file:
CC ?= gcc
CXX ?= g++
CXXFLAGS += -I ../src/ -I ./ -DLINUX -lcurl <- compile option
LDFLAGS += -lrt -lpthread -lcurl <- linker option
Gerard
Solution 4 - C
Depending how bad things are you might need an -L/somewhere in LDFLAGS to let the linker know where the libraries are. ldconfig is supposed to pick them up and find them on every boot but on a new machine it can take a little prodding, like adding a directory to your /etc/ld.so.conf.