(C++11) example to get array length by template method.

array-length.cpp

#include <iostream>

template<typename T, std::size_t N>
std::size_t array_length(const T (&a)[N])
{
    return N;
}

int main(int argc, char *argv[])
{
    int array[10];
    std::cout << array_length(array) << std::endl;
    return 0;
}

Ref.
(JP) http://cpp.aquariuscode.com/array_size_template
(JP) http://www.techscore.com/blog/2013/02/08/how-to-calculate-array-length-in-c-and-cpp/
(JP) http://d.hatena.ne.jp/pknight/20100317/1268796690