Using time.google.com programatically

[רות ומיכאל האפרתי‎]

Are there code samples for obtaining the current date and time from a software program? c++ would be best. 

[Chris Schrier]

The time.google.com service provides NTP, most NTP libraries should work. You can find several examples of NTP clients written in C++ on GitHub and StackOverflow.

I do not know your use case but you should be aware of inaccuracy caused by network latency and understand that changing the system clock, especially backwards, can have unexpected consequences. 

On Tue, Mar 7, 2017 at 7:46 AM, רות ומיכאל האפרתי <myma...@gmail.com> wrote:

Are there code samples for obtaining the current date and time from a software program? c++ would be best. 

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[Eugen S]

I suppose, this question is interesting not only to C++ coders. 

I have to get time on a controller. I can establish UDP connection to an ntp server but no libraries for udp are available for me.

So, can i manually send a request to UDP 216.239.35.0:123 and get a string to parse? I tried sending empty messages with packet sender, but it didn't work.

Or are there any services (not NTP, but constant IP), which can respond my TCP or UDP request with a string containing time and date?

вторник, 7 марта 2017 г., 18:54:55 UTC+3 пользователь Chris Schrier написал:

The time.google.com service provides NTP, most NTP libraries should work. You can find several examples of NTP clients written in C++ on GitHub and StackOverflow.

I do not know your use case but you should be aware of inaccuracy caused by network latency and understand that changing the system clock, especially backwards, can have unexpected consequences. 

On Tue, Mar 7, 2017 at 7:46 AM, רות ומיכאל האפרתי <myma...@gmail.com> wrote:

Are there code samples for obtaining the current date and time from a software program? c++ would be best. 

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[Jamie Wilkinson]

You can send NTP packets to that IP and it will respond to them.  Sending an empty packet won't work.

If you read the NTP v3 spec (RFC 1305) or any later one, and implement that on your controller, then you should have some success.

(You should also be able to send packets to *any* public NTP server, e.g. pool.ntp.org, to test your controller code.)

On 11 March 2017 at 19:43, Eugen S <letit...@gmail.com> wrote:

I suppose, this question is interesting not only to C++ coders. 

I have to get time on a controller. I can establish UDP connection to an ntp server but no libraries for udp are available for me.

So, can i manually send a request to UDP 216.239.35.0:123 and get a string to parse? I tried sending empty messages with packet sender, but it didn't work.

Or are there any services (not NTP, but constant IP), which can respond my TCP or UDP request with a string containing time and date?

вторник, 7 марта 2017 г., 18:54:55 UTC+3 пользователь Chris Schrier написал:

The time.google.com service provides NTP, most NTP libraries should work. You can find several examples of NTP clients written in C++ on GitHub and StackOverflow.

I do not know your use case but you should be aware of inaccuracy caused by network latency and understand that changing the system clock, especially backwards, can have unexpected consequences. 

On Tue, Mar 7, 2017 at 7:46 AM, רות ומיכאל האפרתי <myma...@gmail.com> wrote:

Are there code samples for obtaining the current date and time from a software program? c++ would be best. 

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[Eugen S]

Let this reply stay here:

• send query of 48 bytes: first is 0x1B, others 0x00 to time1.google.com:123 UDP
• get 48 bytes response
• Bytes 41-44 of 48 (if counted from 0 to 47 then you need 40-43) are your timestamp in seconds from year 1900
• enjoy

well-documented implementation https://lettier.github.io/posts/2016-04-26-lets-make-a-ntp-client-in-c.html

get and convert timestamps (epoch, from year 1970) https://www.epochconverter.com

also useful http://www.binaryhexconverter.com/hex-to-decimal-converter

суббота, 11 марта 2017 г., 14:12:21 UTC+3 пользователь Jamie Wilkinson написал:

You can send NTP packets to that IP and it will respond to them.  Sending an empty packet won't work.

If you read the NTP v3 spec (RFC 1305) or any later one, and implement that on your controller, then you should have some success.

(You should also be able to send packets to *any* public NTP server, e.g. pool.ntp.org, to test your controller code.)

On 11 March 2017 at 19:43, Eugen S <letit...@gmail.com> wrote:

I suppose, this question is interesting not only to C++ coders. 

I have to get time on a controller. I can establish UDP connection to an ntp server but no libraries for udp are available for me.

So, can i manually send a request to UDP 216.239.35.0:123 and get a string to parse? I tried sending empty messages with packet sender, but it didn't work.

Or are there any services (not NTP, but constant IP), which can respond my TCP or UDP request with a string containing time and date?

вторник, 7 марта 2017 г., 18:54:55 UTC+3 пользователь Chris Schrier написал:

The time.google.com service provides NTP, most NTP libraries should work. You can find several examples of NTP clients written in C++ on GitHub and StackOverflow.

I do not know your use case but you should be aware of inaccuracy caused by network latency and understand that changing the system clock, especially backwards, can have unexpected consequences. 

On Tue, Mar 7, 2017 at 7:46 AM, רות ומיכאל האפרתי <myma...@gmail.com> wrote:

Are there code samples for obtaining the current date and time from a software program? c++ would be best. 

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[Jamie Wilkinson]

Thanks for the followup, Eugen!

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