Defect Report #271

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Submitter: UK C Panel
Submission Date: 2001-09-07
Source: Clive D.W. Feather <>
Version: 1.2
Date: 2002-05-15
Subject: lacuna in iswctype and towctrans


Consider the calls:

    iswctype (c, wctype (property))
    towctrans (c, wctrans (property))

where property is not valid in the current locale. The wctype and wctrans functions return zero, but the behaviour of iswctype and towctrans is not specified.

I believe it would be useful - and considered natural - for them to return 0 ("c does not have this property") and c ("c is unaffected by this mapping") respectively.

Suggested Technical Corrigendum

Append to

If desc is zero, the iswctype function returns zero (false).

Append to

If desc is zero, the towctrans function returns the value of wc.

Proposed Committee Response

Since no behavior is specified when desc is zero, for either iswctype() or towctrans(), the behavior is undefined. We do not believe it would be appropriate to add new requirements here.

Committee Discussion

The Committee believes this should be considered for a future revision of the Standard.

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