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### 164. do_put() has apparently unused fill argument

Section: 30.4.6.4.2 [locale.time.put.virtuals] Status: TC1 Submitter: Angelika Langer Opened: 1999-07-23 Last modified: 2016-01-28

Priority: Not Prioritized

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Discussion:

In 30.4.6.4.2 [locale.time.put.virtuals] the do_put() function is specified as taking a fill character as an argument, but the description of the function does not say whether the character is used at all and, if so, in which way. The same holds for any format control parameters that are accessible through the ios_base& argument, such as the adjustment or the field width. Is strftime() supposed to use the fill character in any way? In any case, the specification of time_put.do_put() looks inconsistent to me.
Is the signature of do_put() wrong, or is the effects clause incomplete?

Proposed resolution:

Add the following note after 30.4.6.4.2 [locale.time.put.virtuals] paragraph 2:

> [Note: the `fill` argument may be used in the implementation-defined formats, or by derivations. A space character is a reasonable default for this argument. --end Note]

Rationale:

The LWG felt that while the normative text was correct, users need some guidance on what to pass for the `fill` argument since the standard doesn't say how it's used.