Newbie date format questions (strftime)

Projects Programming
1

Hi -- I'm trying to print the current time like this:

char tempstring [128];
struct tm timeinfo;
...
	if (getLocalTime(&timeinfo, 1)) // 1s timeout, but once time acquired from NTP should be immediate
	{
       strftime(tempstring,sizeof(tempstring), "%Y-%m-%d %H:%M:%S", &timeinfo);
       // print tempstring to display, etc.
	}

...it works, but it shows time in 24-hour format, where 3pm is "15". I want 12 hour format, but it zero-pads: %I makes "03". I've read various ways to convince strftime to not zero-pad (%-I, %#I, etc) but none of them seem to work. %r seemed promising but didn't work.

Any way to do this with strftime? Thanks!

2

https://cplusplus.com/reference/ctime/strftime/

%r is 12 hour clock time

3

Yes, but it still has that pesky leading zero on the hours.

4

Thanks! I also tried %r but it didn't print anything... I should say that I'm programming an ESP32 (on the Arduino framework) in vscode/platformIO in case that means anything to this quandary...

5

You could just remove it

6

strftime is easy to understand. if the code works but isn't exactly what you want, check the reference and change the format, probably changing %H to %I or %e for space padded hour

7

You could just roll your own (untested code follows):

	if (getLocalTime(&timeinfo, 1)) // 1s timeout, but once time acquired from NTP should be immediate
	{
       snprintf(tempstring,sizeof(tempstring), "%04u-%02u-%02u %u:%%02u:%02u", 
          timeinfo.tm_year+1900,
          timeinfo.tm_mon+1,
          timeinfo.tm_mday,
          timeinfo.tm_hour % 12 ? timeinfo.tm_hour % 12 : 12,
          timeinfo.tm_min,
          timeinfo.tm_sec);
       // print tempstring to display, etc.
	}

[/quote]

1 Like
8

Thanks all, and thanks van_der_decken for that example custom code -- I'll do that. Much obliged.

9

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