Update README

Clang complains that `nullptr_t` should be `std::nullptr_t

README.md

@@ -175,6 +175,7 @@ svr.Get("/stream", [&](const Request &req, Response &res) {
 
   res.set_content_provider(
     data->size(), // Content length
+    "text/plain", // Content type
     [data](size_t offset, size_t length, DataSink &sink) {
       const auto &d = *data;
       sink.write(&d[offset], std::min(length, DATA_CHUNK_SIZE));
@@ -184,6 +185,25 @@ svr.Get("/stream", [&](const Request &req, Response &res) {
 });
 ```
 
+Without content length:
+
+```cpp
+svr.Get("/stream", [&](const Request &req, Response &res) {
+  res.set_content_provider(
+    "text/plain", // Content type
+    [&](size_t offset, size_t length, DataSink &sink) {
+      if (/* there is still data */) {
+        std::vector<char> data;
+        // prepare data...
+        sink.write(data.data(), data.size());
+      } else {
+        done(); // No more data
+      }
+      return true; // return 'false' if you want to cancel the process.
+    });
+});
+```
+
 ### Chunked transfer encoding
 
 ```cpp
@@ -193,7 +213,7 @@ svr.Get("/chunked", [&](const Request& req, Response& res) {
       sink.write("123", 3);
       sink.write("345", 3);
       sink.write("789", 3);
-      sink.done();
+      sink.done(); // No more data
       return true; // return 'false' if you want to cancel the process.
     }
   );
@@ -286,9 +306,13 @@ int main(void)
 {
   httplib::Client cli("localhost", 1234);
 
-  auto res = cli.Get("/hi");
-  if (res && res->status == 200) {
-    std::cout << res->body << std::endl;
+  if (auto res = cli.Get("/hi")) {
+    if (res->status == 200) {
+      std::cout << res->body << std::endl;
+    }
+  } else {
+    auto err = res.error();
+    ...
   }
 }
 ```
@@ -434,13 +458,12 @@ auto res = cli_.Post(
 httplib::Client client(url, port);
 
 // prints: 0 / 000 bytes => 50% complete
-std::shared_ptr<httplib::Response> res =
-  cli.Get("/", [](uint64_t len, uint64_t total) {
-    printf("%lld / %lld bytes => %d%% complete\n",
-      len, total,
-      (int)(len*100/total));
-    return true; // return 'false' if you want to cancel the request.
-  }
+auto res = cli.Get("/", [](uint64_t len, uint64_t total) {
+  printf("%lld / %lld bytes => %d%% complete\n",
+    len, total,
+    (int)(len*100/total));
+  return true; // return 'false' if you want to cancel the request.
+}
 );
 ```
 

example/client.cc

@@ -23,12 +23,12 @@ int main(void) {
   httplib::Client cli("localhost", 8080);
 #endif
 
-  auto res = cli.Get("/hi");
-  if (res) {
+  if (auto res = cli.Get("/hi")) {
     cout << res->status << endl;
     cout << res->get_header_value("Content-Type") << endl;
     cout << res->body << endl;
   } else {
+    cout << "error code: " << res.error() << std::endl;
 #ifdef CPPHTTPLIB_OPENSSL_SUPPORT
     auto result = cli.get_openssl_verify_result();
     if (result) {

example/simplecli.cc

@@ -17,12 +17,12 @@ int main(void) {
   auto scheme_host_port = "http://localhost:8080";
 #endif
 
-  auto res = httplib::Client(scheme_host_port).Get("/hi");
-
-  if (res) {
+  if (auto res = httplib::Client(scheme_host_port).Get("/hi")) {
     cout << res->status << endl;
     cout << res->get_header_value("Content-Type") << endl;
     cout << res->body << endl;
+  } else {
+    cout << res.error() << endl;
   }
 
   return 0;