In the C and C++ programming languages, #pragma once is a non-standard but widely supported preprocessor directive designed to cause the current source file to be included only once in a single compilation.
During sexual reproduction, fertilization of the ovum (n, 23 chromosomes) by the sperm (n, 23 chromosomes) restores the diploid number and creates a zygote (2n, 46) (awww..) that divides and grows by mitosis to form a multicellular human.
Ovum is simply the female gamete. Since the nucleus of this reproductive cell contains only a half number of chromosomes as a usual cell does have, an ovum is considered as a haploid cell. Ova (plural of ovum) are present in both animals and embryophytes. The female reproductive cell of the plants is called the gametophyte.