Because Halloween is October 31th and Christmas is December 25th, and
Oct(al) 31 "equals" Dec(imal) 25
HAHAHA
That’s a good joke, and I was surprised that I hadn’t known it after learning CS for so many years…
Oh, I read this joke from the interesting book "Expert in C". It’s originally from the great book "The Art of Computer Programming" by Knuth….
What a cold joke…….