cURL C++ Example

curl_example.cpp

#include <iostream>
#include <string>
#include <curl/curl.h>


static size_t WriteCallback(void *contents, size_t size, size_t nmemb, void *userp)
{
    ((std::string*)userp)->append((char*)contents, size * nmemb);
    return size * nmemb;
}

int main(void)
{
  CURL *curl;
  CURLcode res;
  std::string readBuffer;

  curl = curl_easy_init();
  if(curl) {
    curl_easy_setopt(curl, CURLOPT_URL, "http://www.google.com");
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, WriteCallback);
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, &readBuffer);
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);

    std::cout << readBuffer << std::endl;
  }
  return 0;
}

I developed a client which is receiving data from server occasionally. But when I receive first data, then program exists. I tried while loop like windows message loop, but it gives me last data.

How can I stay in program so that I can receive more messages from server.

@alghanmi Hi!

First off, thank you for sharing your code example! It was incredibly helpful for getting me started quickly. However, I wanted to point out a couple of discrepancies that I noticed:

1. Missing global initialization:
   The libcurl documentation recommends using curl_global_init() at the beginning of the program to set up the necessary environment for curl operations. See "Global preparation" section:
   - https://curl.se/libcurl/c/libcurl-tutorial.html
2. Callback prototype mismatch:
   The prototype for the callback function seems to be inconsistent with the one documented on the official libcurl site. The prototype for this callback function is described here:
   - https://curl.se/libcurl/c/CURLOPT_WRITEFUNCTION.html

size_t write_callback(char *ptr, size_t size, size_t nmemb, void *userdata);

On a related note, I've created a more detailed setup documentation and added a simple example as well as a slightly more complex one that includes POST requests, which some may find useful:
- https://github.com/voidlib/cpp-curl-example

Thanks again for your contribution—it was a great starting point for me!

Best regards,
@voiduin

this was the best explanation