How to change the time format from AM/PM to UT?

Question

Mohamed Nedal 2019-12-20

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/497580-how-to-change-the-time-format-from-am-pm-to-ut

编辑： Adam Danz 2019-12-20

采纳的回答： Adam Danz

在 MATLAB Online 中打开

Hi everyone,

Here's what I've tried

t = {'12:24:05'
'10:36:05'
'04:07:55'
'01:25:51'
'01:48:05'}; 
t_final = datetime(t,'Format','hh:mm:ss'); 
t_final = 
23×1 datetime array
   12:24:05
   10:36:05
   04:07:55
   01:25:51
   01:48:05 
   
t_final.Format = 'default'; 
t_final = 
5×1 datetime array
   20-Dec-2019 00:24:05
   20-Dec-2019 10:36:05
   20-Dec-2019 04:07:55
   20-Dec-2019 01:25:51
   20-Dec-2019 01:48:05 

I get the date of today with the time format I need. I tried to extract only the time but it gives the previous format (am/pm).

Any ideas?

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Answer 1

Adam Danz 2019-12-20

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/497580-how-to-change-the-time-format-from-am-pm-to-ut#answer_407246

编辑：Adam Danz 2019-12-20

在 MATLAB Online 中打开

Datetime values can be formatted to show only the time component but the time component cannot be separated from a date. To show only the time component in 24-hour clock format, use upper case HH

t_final = datetime(t,'Format','HH:mm:ss')
%   6×1 datetime array
%    12:24:05
%    10:36:05
%    04:07:55
%    01:25:51
%    01:48:05
%    13:30:10

Another possibility is using durations instead of datetime.

t_final = duration(t); 
%   6×1 duration array
%    12:24:05
%    10:36:05
%    04:07:55
%    01:25:51
%    01:48:05
%    13:30:10

Does that achieve your goal?

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Mohamed Nedal 2019-12-20

在 MATLAB Online 中打开

The expected format would be like this

t_final = {'00:24:05'
'10:36:05'
'04:07:55'
'01:25:51'
'01:48:05'}; 

I tried to the use upper case HH

t_final = datetime(t,'Format','HH:mm:ss');

but there is no effect, it's the same.

Adam Danz 2019-12-20

编辑：Adam Danz 2019-12-20

Why should '12:24:05' be interpreted as '00:24:05'? With a 24-hr clock, 12:00 means noon. With Am/Pm format, the input needs to include the AM/PM otherwise we have no idea how to interpret 12:00.

If you're using 24-hour clock and you want 12:24:05 to be interpreted as 24:24:05 it must include an AM PM in the input -or- there must be some kind of context to the inputs such as "the first value will always be in the AM cycle and the following values are in ascending order".

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