Upload a file using c++ via curl

Hi Greg-DB , thanks for replying so quick

I followed your suggestion and tried tp use std::ifstream like this:

CURL *curl;
    CURLcode res;

    /* In windows, this will init the winsock stuff */
    curl_global_init(CURL_GLOBAL_ALL);

    /* get a curl handle */
    curl = curl_easy_init();

    string test = "D:\\Desktop\\test.txt";

    std::ifstream file(test);

    if(curl)
    {
        printf ("Running curl test.\n");

        struct curl_slist *headers=NULL; /* init to NULL is important */
        headers = curl_slist_append(headers, "Authorization: Bearer <my_access_token>");
        headers = curl_slist_append(headers, "Content-Type: application/octet-stream");
        headers = curl_slist_append(headers, "Dropbox-API-Arg: {\"path\":\"/test.txt\"}");
        curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);

        curl_easy_setopt(curl, CURLOPT_URL, "https://content.dropboxapi.com/2/files/upload");
        curl_easy_setopt(curl, CURLOPT_POSTFIELDS, file);

        curl_easy_setopt (curl, CURLOPT_SSL_VERIFYPEER, FALSE);

        /* 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);

        printf ("\nFinished curl test.\n");

    }
    curl_global_cleanup();

    printf ("Done!\n");

but it didn't compile displaying this error:

C:\Min.GW\curl-7.64.1-win64-mingw\include\curl\curl.h|2857|error: use of deleted function 'std::basic_ifstream<_CharT, _Traits>::basic_ifstream(const std::basic_ifstream<_CharT, _Traits>&) [with _CharT = char; _Traits = std::char_traits<char>]'|

But before that I had this code:

CURL *curl;
    CURLcode res;

    /* In windows, this will init the winsock stuff */
    curl_global_init(CURL_GLOBAL_ALL);

    /* get a curl handle */
    curl = curl_easy_init();
    

    if(curl)
    {
        printf ("Running curl test.\n");

        struct curl_slist *headers=NULL; /* init to NULL is important */
        headers = curl_slist_append(headers, "Authorization: Bearer <my_access_token>");
        headers = curl_slist_append(headers, "Content-Type: application/octet-stream");
        headers = curl_slist_append(headers, "Dropbox-API-Arg: {\"path\":\"/D:\\Desktop\\test.txt\"}");
        curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);

        curl_easy_setopt(curl, CURLOPT_URL, "https://content.dropboxapi.com/2/files/upload");
        

        curl_easy_setopt (curl, CURLOPT_SSL_VERIFYPEER, FALSE);

        /* 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);

        printf ("\nFinished curl test.\n");

    }
    curl_global_cleanup();

    printf ("Done!\n");

And this would just create new folders  and files in my account
Don't know if the codes I posted might be too long, the difference between the two is only at this line:

curl_easy_setopt(curl, CURLOPT_POSTFIELDS, "test data for upload");