Arrays can only be passed by reference, actually:
void foo(double (&bar)[10])
{
}
This prevents you from doing things like:
double arr[20];
foo(arr); // won't compile
To be able to pass an arbitrary size array to foo, make it a template and capture the size of the array at compile time:
template<typename T, size_t N>
void foo(T (&bar)[N])
{
// use N here
}
You should seriously consider using std::vector, or if you have a compiler that supports c++11, std::array.