The #else directive can be added to a conditional to provide alternative text to be used if the condition is false. The following is what it resembles.
#if expression text-if-true #else /* Not expression */
text-if-false
#endif /* Not expression */If expression is nonzero, and thus the text-if-true is active, then #else acts like a failing conditional and the text-if-false is ignored. Contrarily, if the #if conditional fails, the text-if-false is considered included. 0