Section: 31.7.6.5 [ostream.manip] Status: CD1 Submitter: PremAnand M. Rao Opened: 2001-08-27 Last modified: 2016-01-28
Priority: Not Prioritized
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Discussion:
A footnote in 31.7.6.5 [ostream.manip] states:
[Footnote: The effect of executing cout << endl is to insert a newline character in the output sequence controlled by cout, then synchronize it with any external file with which it might be associated. --- end foonote]
Does the term "file" here refer to the external device? This leads to some implementation ambiguity on systems with fully buffered files where a newline does not cause a flush to the device.
Choosing to sync with the device leads to significant performance penalties for each call to endl, while not sync-ing leads to errors under special circumstances.
I could not find any other statement that explicitly defined the behavior one way or the other.
Proposed resolution:
Remove footnote 300 from section 31.7.6.5 [ostream.manip].
Rationale:
We already have normative text saying what endl does: it
inserts a newline character and calls flush. This footnote
is at best redundant, at worst (as this issue says) misleading,
because it appears to make promises about what flush
does.