Can I check in C(++) if an array is all 0 (or false)?

Question

Can I check in C(++) if an array is all 0 (or false) without iterating/looping over every single value and without allocating a new array of the same size (to use memc

Answer 1

Assume that you have an array of N element, you can do a bit check against a set of base vectors.

For example, you have a 15-element array you want to test.

You can test it against an 8-element zero array, an 4-element zero array, a 2-element zero array and a 1-element zero array.

You only have to allocate these elements once given that you know the maximum size of arrays you want to test. Furthermore, the test can be done in parallel (and with assembly intrinsic if necessary).

Further improvement in term of memory allocation can be done with using only an 8-element array since a 4-element zero array is simply the first half of the 8-element zero array.

Answer 2

Consider using boost::dynamic_bitset instead. It has a none member and several other std::bitset-like operations, but its length can be set at runtime.