Function croaring_sys::roaring_bitmap_rank

pub unsafe extern "C" fn roaring_bitmap_rank(
    r: *const roaring_bitmap_t,
    x: u32
) -> u64

roaring_bitmap_rank returns the number of integers that are smaller or equal to x. Thus if x is the first element, this function will return 1. If x is smaller than the smallest element, this function will return 0.

The indexing convention differs between roaring_bitmap_select and roaring_bitmap_rank: roaring_bitmap_select refers to the smallest value as having index 0, whereas roaring_bitmap_rank returns 1 when ranking the smallest value.