CODEWITHSUNDEEP
rubytime
Yehudi
Yehudi

Reputation: 199

ruby strftime give wrong time

For Example, timestamp is 1403667010.574 , use Time.at(1403667010.574).strftime('%Y-%m-%d %H:%M:%S.%L %z'), then the resuit is 

"2014-06-25 03:30:10.573 +0000"

it loss 1ms on the result. Is that a bug of ruby?

For me, the major problem is, if I convert the time string by Time.parse("2014-06-25 03:30:10.573 +0000").to_f, the result would become 1403667010.573. It's not equivalent to origin value

Upvotes: 1

Views: 184

Answers (1)

Sergio Tulentsev
Sergio Tulentsev

Reputation: 230336

This is how floating point numbers work. They are approximately precise (not absolutely).

t = Time.at(1403667010.574)
t.strftime('%Y-%m-%d %H:%M:%S.%L %z') # => "2014-06-25 07:30:10.573 +0400"

# more precision
t.strftime('%Y-%m-%d %H:%M:%S.%6N %z') # => "2014-06-25 07:30:10.573999 +0400"

# even more precision
t.strftime('%Y-%m-%d %H:%M:%S.%10N %z') # => "2014-06-25 07:30:10.5739998817 +0400"

In addition, this is what Time#strftime documentation says about %L flag:

%L - Millisecond of the second (000..999) The digits under millisecond are truncated to not produce 1000.

So, the value .573999 is simply truncated (not rounded) to .573

Upvotes: 5

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