This looks like a bug in the December 1996 draft, or if not,
specification of a questionable feature.

Paragraph 5-6 of 21.3.6.8 [lib.string::compare] says:

 int compare(size_type pos, size_type n1,
      charT *s, size_type n2 = npos ) const;

 Returns:

 basic_string<charT,traits,Allocator>(*this,pos,n1).compare(
       basic_string<charT,traits,Allocator>(s,n2))


Paragraph 5-7 of 21.3.1 [lib.string.cons] says:

 basic_string(const charT* s, size_type n,
       const Allocator& a = Allocator())
 ...
 Throws: out_of_range if n==npos

So if I call method compare with the default value for argument n2,
the method *must* throw an exception.  What good is the default
value then?  Why not leave out the default and catch the omission at
compile time?

Arch D. Robison       Kuck & Associates Inc.
robison@kai.com       1906 Fox Drive
217-356-2288        Champaign IL 61820
Lead Developer for KAI C++     http://www.kai.com/C_plus_plus/index.html
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