[ruby-core:107427] [Ruby master Bug#18565] strptime reports invalid date when string is "130AM" and format string is '%I:%M%p'

Issue #18565 has been updated by jeremyevans0 (Jeremy Evans).

Status changed from Open to Rejected

I don't think this is a bug.  `strptime` is supposed to be the inverse of `strftime`:

```ruby
DateTime.now.strftime('%I%M%p')
# => "0617PM"
DateTime.now.strftime('%l%M%p')
# => " 617PM"
``` 

If you pass the same formats to `strptime`, it will work correctly:

```ruby
DateTime.strptime("0130PM", '%I%M%p')
# => #<DateTime: 2022-02-01T13:30:00+00:00 ((2459612j,48600s,0n),+0s,2299161j)>
DateTime.strptime(" 130PM", '%l%M%p')
# => #<DateTime: 2022-02-01T13:30:00+00:00 ((2459612j,48600s,0n),+0s,2299161j)>
```

The fact that `1:` works with the `%I`/`%l` formats is due to implementation details, not by design, and should not be relied on. 

----------------------------------------
Bug #18565: strptime reports invalid date when string is "130AM" and format string is '%I:%M%p'
https://bugs.ruby-lang.org/issues/18565#change-96326

* Author: CaryInVictoria (Cary Swoveland)
* Status: Rejected
* Priority: Normal
* ruby -v: 2.7.1
* Backport: 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN
----------------------------------------
`DateTime.strptime("1:30PM", '%I:%M%p')` and `DateTime.strptime("1:30PM", '%l:%M%p')` both return
`#<DateTime: 2022-02-01T13:30:00+00:00 ((2459612j,48600s,0n),+0s,2299161j)>`

`DateTime.strptime("130PM", '%I%M%p')` and `DateTime.strptime("130PM", '%l%M%p')`
both raise the exception `Date::Error: invalid date`

I don't understand why an exception should be raised when the string is `"130PM"`. Is this a bug?



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