итог:вариант 15

lab_3.xcodeproj/xcshareddata/xcschemes/lab_3.xcscheme

@@ -50,6 +50,12 @@
             ReferencedContainer = "container:lab_3.xcodeproj">
          </BuildableReference>
       </BuildableProductRunnable>
+      <CommandLineArguments>
+         <CommandLineArgument
+            argument = "http://uit.mpei.ru/study/courses/cs/lab03/marks.txt"
+            isEnabled = "YES">
+         </CommandLineArgument>
+      </CommandLineArguments>
    </LaunchAction>
    <ProfileAction
       buildConfiguration = "Release"

main.cpp

@@ -34,13 +34,22 @@ Input input_data(istream& in, bool prompt)
 }
 
 size_t
-write_data(void* items, size_t item_size, size_t item_count, void* ctx) {
-    stringstream* buffer = reinterpret_cast<stringstream*>(ctx);
+write_data(void* items, size_t item_size, size_t item_count, void* ctx)
+{
     size_t data_size = item_size * item_count;
+    stringstream *buffer = reinterpret_cast<stringstream*>(ctx);
     (*buffer).write(reinterpret_cast<const char*>(items), data_size);
     return data_size;
 }
 
+size_t
+write_header(char* buffer, size_t size, size_t nitems, void* userdata)
+{
+    cerr << "Headers: " << buffer << endl;
+    return size * nitems;
+}
+
+
 Input
 download(const string& adress){
     curl_global_init(CURL_GLOBAL_ALL);
@@ -52,6 +61,8 @@ download(const string& adress){
         curl_easy_setopt(curl, CURLOPT_URL, adress.c_str());
         curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_data);
         curl_easy_setopt(curl, CURLOPT_WRITEDATA, &buffer);
+        curl_easy_setopt(curl, CURLOPT_HEADERFUNCTION, write_header);
+        curl_easy_setopt(curl, CURLOPT_HEADERDATA, NULL);
         res = curl_easy_perform(curl);
         if (res != CURLE_OK)
         {