It would seem that the "for each" style of syntax available in C++11 permits array iteration without knowledge of the actual size of the array (number of elements). I assume, since it is part of the new standard, that this is perfectly safe, even for C arrays. Typically, you must also separately know the size of a C array before manipulating it, but I want verification from anyone experienced with this new C++ technique that it works exactly as you'd expect:
extern float bunch[100];
for (float &f : bunch) {
f += someNumber;
}
Is there anything I should know about non-obvious side effects or disadvantages to this technique? It doesn't show much in code I see, probably because most of the code was written before this was in the standard. Want to make sure its rare usage isn't because of some other reason not well-known.
There is nothing strange or unsafe about that usage. The array's size is known at compile time, so it can be used in the loop. This is an example of a template function that allows you to find out the length of an array:
template< class T, std::size_t N >
std::size_t length( const T (&)[N] )
{
return N;
}
Foo f[5];
std::cout << length(f) << "\n";
This should make it clear that you cannot use this technique, or range based loops, on dynamically sized C-style arrays.
Of course, if you have range based loops then you should also have std::array (if not, you can probably get ti from std::tr1 or boost), so you can avoid the C-style array entirely:
extern std::array<float, 100> bunch;
for (auto &f : bunch) {
f += someNumber;
}