Issue #10588 has been reported by Imran Ashraf.

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Bug #10588: Invalid Dates
https://bugs.ruby-lang.org/issues/10588

* Author: Imran Ashraf
* Status: Open
* Priority: Normal
* Assignee: 
* Category: 
* Target version: 
* ruby -v: 2.0.0-p481
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN
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I was in the process of implementing a date-routine, which could prevent possible out-of-range/invalid date values.

The interpreter, rightfully, threw an out-of range error, when I tried any of the following:
puts Time.mktime 2014, 13, 32
puts Time.mktime 2014, 13, 32

No surprises there. However, when I tried:
puts Time.mktime 2014, 11, 31
The interpreter, happily produced: 2014-12-01.

A little intrigued, I went ahead and tried the following routine:
1.upto(12){|month| puts Time.mktime 2014, month, 31}

Result:
2014-01-31      ok
2014-03-03      ???
2014-03-31      ok
2014-05-01      ???
2014-05-31      ok
2014-07-01      ???
2014-07-31      ok
2014-08-31      ok
2014-10-01      ???
2014-10-31      ok
2014-12-01      ???
2014-12-31      ok

I hope, I've been able to describe this issue adequately.

Thanks Matz & all the contributors for bringing this wonderful tool to us.

Regards.



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