9dfa2e57   
   From: daniel.kruegler@googlemail.com   
      
   On 2011-06-24 09:26, Joshua Lehrer wrote:   
   > Consider this code:   
   >   
   >    std::vector  v;   
   >    v.reserve(32);   
   >    v.resize(1);   
   >   
   > After the reserve call the capacity should be at least 32.  Can the   
   > resize call cause a reallocation?   
      
   No.   
      
   > The standard says this about reserve():   
   >    It is guaranteed that no reallocation takes place during insertions   
   > that happen after   
   >    a call to reserve() until the time when an insertion would make the   
   > size of the vector greater than   
   >    the value of capacity().   
   >   
   > Does the resize call here count as an "insertion"?  C++98 says that   
   > resize(size_type sz, T c = T()) should act like insert(end(), sz-   
   > size(), c); here.  C++0x draft N3092 only says that resize(size_type   
   > sz) should "append" a default constructed element to the vector.   
      
   It counts as insertion, but it is unfortunate that the semantics of both   
   resize overloads are described differently (A new issue has been opened   
   to keep them in sync both the currently proposed wording suggests to use   
   the term "append" now in both places). Note that the usage of "append"   
   within the container description is quite common, e.g. the general   
   effects of push_back are described in Table 101 — "Optional sequence   
   container operations" as "append". It would be nice, if this clause   
   would say somewhere: "Within this sub-clauses the term append is used   
   and means an insertion at the end of a sequence", but alas this does not   
   exist. I'm not sure that this is a real issue, because I have not found   
   yet an implementation where this was indeed misinterpreted (and what   
   would be the misinterpretation?). IMO this is more an editorial problem   
   than a real issue.   
      
   > also, what about this code:   
   >   
   > std::vector  v;   
   > v.reserve(32);   
   > v.resize(31);   
   > v.resize(1);   
   > v.resize(0);   
   > v.resize(32);   
   >   
   > are there any reallocations allowed in the above code after the call   
   > to reserve?   
      
   No, because none of the resize() calls produces a size that exceeds the   
   capacity at this point. In fact, the capacity is never changed after the   
   call of reserve in this example code.   
      
   HTH & Greetings from Bremen,   
      
   Daniel Krügler   
      
      
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