docs/examples/protofeats.c: Outputs all protocols and features

Showing off one way to get to char pointer arrays of info returned by
curl_version_info()

Closes #10991

docs/examples/Makefile.inc

@@ -97,6 +97,7 @@ check_PROGRAMS = \
   postit2 \
   postit2-formadd \
   progressfunc \
+  protofeats \
   resolve \
   sendrecv \
   sepheaders \

docs/examples/protofeats.c

@@ -0,0 +1,52 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at https://curl.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ * SPDX-License-Identifier: curl
+ *
+ ***************************************************************************/
+/* <DESC>
+ * Outputs all protocols and features supported
+ * </DESC>
+ */
+#include <stdio.h>
+#include <curl/curl.h>
+
+#if !CURL_AT_LEAST_VERSION(7,87,0)
+#error "too old libcurl"
+#endif
+
+int main(void)
+{
+  curl_version_info_data *ver;
+  const char *const *ptr;
+
+  curl_global_init(CURL_GLOBAL_ALL);
+
+  ver = curl_version_info(CURLVERSION_NOW);
+  printf("Protocols:\n");
+  for(ptr = ver->protocols; *ptr; ++ptr)
+    printf("  %s\n", *ptr);
+  printf("Features:\n");
+  for(ptr = ver->feature_names; *ptr; ++ptr)
+    printf("  %s\n", *ptr);
+
+  curl_global_cleanup();
+  return 0;
+}