How does a “for each” loop in C++ know the length of an array

Question

I was looking at the following example from http://www.cplusplus.com/doc/tutorial/arrays/ and I couldn\'t figure out how the 2nd for loop worked. How can the for loop know w

Answer 1

The compiler knows the number of elements of the array due to the array definition. So it uses expressions myarray and myarray + 3 to traverse the array.

In fact the loop looks the following way

for ( auto first = myarray, last = myarray + 3; first != last; ++first )
{
   auto elem = *first;
   cout << elem << '\n';
}

Take into account that the range-based for statement use neither std::begin() nor std::end() for arrays as others wrote here.:)

According to the C++ Standard

— if _RangeT is an array type, begin-expr and end-expr are __range and __range + __bound, respectively, where __bound is the array bound. If _RangeT is an array of unknown size or an array of incomplete type, the program is ill-formed;