The loop continues until i transitions from 0 to 0 minus 1. 0-1 in this case actually doesn't equal -1 since size_t is an unsigned type, instead it wraps around

The loop continues until i transitions from 0 to 0 minus 1. 0-1 in this case actually doesn't equal -1 since size_t is an unsigned type, instead it wraps around to be the largest possible positive integer instead. TLDR; yes as you speculate it terminates when the number underflows.