How to properly send data via POSTFIELDS using CURL?
If you write the same code in Python, it will work and the site gives a response of 200, but in C++ it gives a response of 400. As I understand it, the problem is in postfields, although I could be wrong

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

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

int main() {
    setlocale(LC_CTYPE, "ru_RU.UTF-8");
    curl_global_init(CURL_GLOBAL_ALL);

    CURL* curl;
    CURLcode res;
    
    std::string text;

    struct curl_slist* list = NULL;
    list = curl_slist_append(list, "X-Requested-With: XMLHttpRequest");
    list = curl_slist_append(list, "Cookie: __ddg2_=0");

    curl = curl_easy_init();
    if (curl) {
        curl_easy_setopt(curl, CURLOPT_COOKIEFILE, "");

        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writeCallback);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, &text);

        curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
        curl_easy_setopt(curl, CURLOPT_HTTPHEADER, list);

        res = curl_easy_perform(curl);
        if (res != CURLE_OK)
            return 1;

        std::string token = text.erase(0, text.find("<input type="hidden" name="_xfToken" value="") + 44);
        token = token.erase(token.find("""), token.size());
        text = "";

        curl_easy_setopt(curl, CURLOPT_POST, 1);
        curl_easy_setopt(curl, CURLOPT_COPYPOSTFIELDS, "_xfToken=" + token + "&server=ru&id=26");

        res = curl_easy_perform(curl);
        if (res != CURLE_OK)
            return 2;

        curl_easy_cleanup(curl);
    }
    curl_global_cleanup();
}

I tried using POSTFIELDS, COPYPOSTFIELDS and encoding data in it