Merge pull request MicrosoftDocs#3538 from corob-msft/docs/corob/chrono-3

Add C++20 chrono free functions

Author: PRMerger18

docs/standard-library/chrono-functions.md

@@ -341,17 +341,13 @@ The input stream, *`is`*
 #include <chrono>
 #include <iostream>
 
-using namespace std;
-using namespace std::chrono;
-
-int Main()
+int main()
 {
     std::istringstream str{ "22" };
-	std::basic_istream<char> stream{ str.rdbuf() };
-	std::chrono::day d;
-	std::chrono::from_stream(stream, "%d", d);
-	std::cout << d << "\n";
-
+    std::basic_istream<char> stream{ str.rdbuf() };
+    std::chrono::day d;
+    std::chrono::from_stream(stream, "%d", d);
+    std::cout << d << "\n";
     return 0;
 }
 ```
@@ -398,8 +394,8 @@ The format may be one of these strings:
 | Specifier | Description |
 |--|--|
 | `%j` |  If the type being formatted is a specialization of duration, the decimal number of days without padding. Otherwise, the day of the year as a decimal number. `Jan 1` is `001`. If the result is fewer than three digits, it's left-padded with `0` (zero) to three digits. |
-| `%U`<br>`%0U` | The week number of the year as a decimal number. The first Sunday of the year is the first day of week `01`. Days of the same year before that week are in week `00`. If the result is a single digit, it's prefixed with `0` (zero).<br>`%OU` (letter `O`, not zero) produces the locale’s alternative representation. |
-| `%W`<br>`%OW` |The week number of the year as a decimal number. The first Monday of the year is the first day of week `01`. Days of the same year before that week are in week `00`.<br>If the result is a single digit, it's prefixed with `0` (zero).<br>``%OW` (letter `O`, not zero) produces the locale’s alternative representation. |
+| `%U`<br>`%0U` | The week number of the year as a decimal number. The first Sunday of the year is the first day of week `01`. Days of the same year before that week are in week `00`. If the result is a single digit, it's prefixed with `0` (zero).<br>`%OU` (letter `O`, not zero) produces the locale's alternative representation. |
+| `%W`<br>`%OW` |The week number of the year as a decimal number. The first Monday of the year is the first day of week `01`. Days of the same year before that week are in week `00`.<br>If the result is a single digit, it's prefixed with `0` (zero).<br>`%OW` (letter `O`, not zero) produces the locale's alternative representation. |
 
 ### Time of day
 
@@ -461,7 +457,7 @@ If *`abbrev`* isn't `nullptr`, and the format specifier `%Z` is specified, and t
 *`offset`*\
 If *`offset`* isn't `nullptr`, and the format specifier `%z` or modified variant such as `%Ez` or `%0z` is specified, and the parse is successful, then *`offset`* points to the parsed value.
 
-### Which flags can be use which types
+### Flags by type
 
 | Class | Specifier/Flag |
 |--|--|
@@ -846,4 +842,4 @@ Returns a `string` that contains the latest remote database version.
 [`chrono` operators](./chrono-operators.md)\
 [`duration` class](./duration-class.md)\
 [`time_point` class](./time-point-class.md)\
-[`time_zone` class](./time-zone-class.md)
+[`time_zone` class](./time-zone-class.md)

docs/standard-library/chrono.md

@@ -1,9 +1,8 @@
 ---
 description: "Learn more about: <chrono>"
 title: "<chrono>"
-ms.date: "05/07/2019"
+ms.date: 04/29/2021
 f1_keywords: ["<chrono>", "chrono/std::chrono::nanoseconds", "chrono/std::chrono::minutes", "chrono/std::chrono::seconds", "chrono/std::chrono::hours", "chrono/std::chrono::milliseconds", "chrono/std::chrono::microseconds"]
-ms.assetid: 844de749-f306-482e-89bc-6f53c99c8324
 ---
 # `<chrono>`
 

docs/standard-library/leap-second-class.md

@@ -78,4 +78,4 @@ Microsoft C++ supports `leap_second::value` starting in Visual Studio 2019 versi
 [`<chrono>`](./chrono.md)
 [`get_leap_second_info` function](./chrono-functions.md#std-chrono-get-leap-second-info)\
 [Header files reference](./cpp-standard-library-header-files.md)\
-[`leap_second_info` struct](./leap-second-info-struct.md)
+[`leap_second_info` struct](./leap-second-info-struct.md)

docs/standard-library/leap-second-info-struct.md

@@ -40,4 +40,4 @@ namespace std::chrono {
 [`<chrono>`](./chrono.md)\
 [`get_leap_second_info`](./chrono-functions.md#std-chrono-get-leap-second-info)\
 [Header files reference](./cpp-standard-library-header-files.md)\
-[`leap_second` class](./leap-second-class.md)
+[`leap_second` class](./leap-second-class.md)

docs/standard-library/time-zone-class.md

@@ -146,6 +146,7 @@ The function template `to_sys` has two overloads that convert a `local_time` to
 template<class Duration>
 sys_time<common_type_t<Duration, seconds>>
 to_sys(const local_time<Duration>& lt) const;  // Since C++20
+
 template<class Duration>
 sys_time<common_type_t<Duration, seconds>>
 to_sys(const local_time<Duration>& lt, choose z) const;  // Since C++20
@@ -177,4 +178,4 @@ Microsoft C++ supports `time_zone::to_sys` starting in Visual Studio 2019 versio
 ## See also
 
 [Header files reference](./cpp-standard-library-header-files.md)\
-[`<chrono>`](./chrono.md)
+[`<chrono>`](./chrono.md)