Environment of for-loop-incrementation-part

Hi,

in what environment is the incrementation-part (3rd part) of a
for loop executed?

Or, is the following example valid C++ ? (g++-4.2.2 doesn't accept it)

struct Auto_Type;
typedef Auto_Type  *Auto_ptr;

struct Auto_Type {
   Auto_ptr next;
};


int main() {
   Auto_ptr  Head = 0, Tail= 0;

   // (Verarbeiten,) Ausgabe und Löschen der Elemente

   for ( Auto_ptr Auto= Head; Auto; Auto= Auto_next ) {// valid ?
     Auto_ptr Auto_next= Auto->next;  // <<<<<<<<<<  defined only now
     delete Auto;
   }
}


Many thanks for your comment,

Helmut Jarausch

Lehrstuhl fuer Numerische Mathematik
RWTH - Aachen University
D 52056 Aachen, Germany

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