Updated Examples and Recipes (markdown)

Examples-and-Recipes.md

@@ -3,6 +3,7 @@ This page contains examples and recipes contributed by community members. Feel f
 ##Contents
 - [The current local time](#localtime)
 - [The current time somewhere else](#elsetime)
+- [Get the current difference between any two arbitrary time zones](#deltatz)
 - [Obtaining a `time_point` from `y/m/d h:m:s` components](#time_point_to_components)
 - [Obtaining `y/m/d h:m:s` components from a `time_point`](#components_to_time_point)
 - [Normalizing `y/m/d` when it is `!ok()`](#normalize)
@@ -71,6 +72,38 @@ This outputs the current time in Shanghai, for example:
 
 All IANA timezone names (or links -- aliases to timezones) are supported.
 
+<a name="deltatz"></a>
+### Get the current difference between any two arbitrary time zones
+(by [Howard Hinnant](https://github.com/HowardHinnant))
+
+Would you just like to know how many hours ahead or behind your friend is in another time zone?  Here's how you do that with this library.
+
+    #include "tz.h"
+    #include <iostream>
+
+    int
+    main()
+    {
+        auto current_time = std::chrono::system_clock::now();
+        auto la = date::make_zoned("America/Los_Angeles", current_time);
+        auto sy = date::make_zoned("Australia/Sydney", current_time);
+        std::cout << date::make_time(sy.get_local_time() - la.get_local_time()) << '\n';
+    }
+
+Let's say you want to find out how many hours ahead Sydney is from LA (now).  First get the current UTC time.  Then create a `zoned_time` for both "America/Los_Angeles" and "Australia/Sydney" using that current UTC time.  Then subtract their `local_time`s.  `make_time` is a handy formatting tool for printing out that duration:
+
+    17:00:00.000000
+
+Because we did not specify otherwise, the default behavior is to give us the full precision of `system_clock::time_point`.  If you would prefer other behavior (e.g. minutes precision), that is easily accomplished with just a little more work.  `using` directives make the code a little more readable:
+
+    using namespace date;
+    using namespace std::chrono;
+    std::cout << make_time(floor<minutes>(sy.get_local_time() - la.get_local_time())) << '\n';
+
+And now the output is:
+
+    17:00
+
 <a name="time_point_to_components"></a>
 ### Obtaining a `time_point` from `y/m/d h:m:s` components
 (by [ecorm](https://github.com/ecorm))