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.
A human gamete contains 23 unpaired chromosomes. For example, in a spermatozoa, there are 22 unpaired autosomes and one sex chromosome, either an X chromosome for a female or a Y chromosome for a male. Gametes are produced through a specific type of cell division called meiosis, according to 3DScience.com.