Love them (as a sci-fi geek) or loathe them (as a claustrophobe), Nice's 24-hour self-cleaning toilets are here to stay. These mechanical WCs (you'll find 20 of them around the city) are free but allow limited time for dawdling: you have precisely 15 minutes before being (ooh-la-la!) exposed to passers-by. Green means libre (vacant) and red means occupé (occupied).
There are also 11 pay toilets (adult/child €0.50/free), including the centrally located ones along Promenade du Paillon.
Some older establishments and motorway stops still have the hole-in-the-floor toilettes à la turque (squat toilets). Provided you hover, these are actually very hygienic, but take care not to get soaked by the flush.
Keep some loose change handy for tipping toilet attendants, who keep a hawk-like eye on many of Nice's public toilets.
The French are completely blasé about unisex toilets, so save your blushes when tiptoeing past the urinals to reach the ladies' loo.