curl.c:
#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://example.com");
 
    /* Perform the request, res will get the return code */ 
    res = curl_easy_perform(curl);
    /* Check for errors */ 
    if(res != CURLE_OK)
      fprintf(stderr, "curl_easy_perform() failed: %s\n",
              curl_easy_strerror(res));
 
    /* always cleanup */ 
    curl_easy_cleanup(curl);
  }
  return 0;
}

----------

j@laptop:~/Desktop/ctest$ gcc -c curl.c
j@laptop:~/Desktop/ctest$ gcc -lcurl curl.o
curl.o: In function `main':
curl.c:(.text+0x99): undefined reference to `curl_easy_init'
curl.c:(.text+0xc6): undefined reference to `curl_easy_setopt'
curl.c:(.text+0xd2): undefined reference to `curl_easy_perform'
curl.c:(.text+0xe5): undefined reference to `curl_easy_strerror'
curl.c:(.text+0x10d): undefined reference to `curl_easy_cleanup'
collect2: Fehler: ld gab 1 als Ende-Status zurück