From: daniel.kruegler@googlemail.com   
      
   Am 05.10.2011 00:39, schrieb Daniel Krügler:   
   > Am 04.10.2011 20:50, schrieb gast128@hotmail.com:   
   >> Hello all,   
   >>   
   >> Item 16 of Scott Meyers 'Effective STL' describes that a vector can be   
   >> used as a buffer for C API (output) functions, since its underlying   
   >> memory layout is guaranteed to be the same, i.e.   
   >>   
   >> size_t fillArray(double* pArray, size_t n)   
   >>   
   >> std::vector v(10);   
   >> fillArray(&v[0], v.size());   
   >>   
   >> It also explicitly describes that this is only true for vectors and   
   >> not for (basic_)string's. This is kinda of pity since strings have   
   >> often small string optimizations (e.g. the string in Plauger's STL has   
   >> a fixed buffer of 16 characters and switches to the dynamic one if   
   >> strings are longer).   
   >   
   > As of C++11 the idiom is now safe for std::basic_string as well (But   
   > beware of the empty case!). Note that the recommended way of using   
   > either of is now via   
   >   
   > fillArray(v.data(), v.size());   
   >   
   > because this will also work for empty vector/string (Note that the   
   > returned pointer value is unspecified for the empty case, so do not rely   
   > on the assumption that it would be a nullptr).   
      
   Let me clarify here, that the unspecified pointer value applies to   
   vector and array. For std::basic_string the pointer value is   
   specified to be one pointing to a value-initialized character. In this   
   sense, the usage of   
      
   fillArray(&v[0], v.size());   
      
   is defined for basic_string since C++11 even for the empty case. I still   
   recommend to use the   
      
   fillArray(v.data(), v.size());   
      
   because that also works for other containers (array, vector) in the   
   empty case.   
      
   Greetings from Bremen,   
      
   Daniel Krügler   
      
      
      
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