How to store curl responds in a variable in c - c

Question

I am trying to generate curl get request using c program .Here I need to store the response in a variable and I tried with the following code.
#include <stdio.h>
#include <stdlib.h>
#include <curl/curl.h>
function_pt(void *ptr, size_t size, size_t nmemb, void *stream){
char **response_ptr = (char**)stream;
*response_ptr = strndup(ptr, (size_t)(size *nmemb));
}
int main(void)
{
CURL *curl;
CURLcode res;
char *response =calloc(1,sizeof(char));
curl = curl_easy_init();
if(curl) {
curl_easy_setopt(curl, CURLOPT_URL, "http://example.com");
curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, function_pt);
curl_easy_setopt(curl, CURLOPT_WRITEDATA, &response);
res=curl_easy_perform(curl);
curl_easy_cleanup(curl);
printf("%s\n",response);
}
return 0;
}
The data I get form http get request is real time,so i need to continue with the get request and store value in a variable in an iterative manner,only so that I can use the data in all other parts of the program.But the following code works only once and then exit.
How can I do it? Are there any other methods to generate http get request?

Answer 1

You don't need to calloc() the pointer if you are going to strndup() the original string, assuming that the response is a string is not good because that is not necessarily true.
I would suggest a structure where you can also store the length of the response, so if it's not text but for example a jpeg file nothing bad will happen, and you should not call printf() unless you check from the response headers that the response is indeed text, and it will be nul terminated afaik.