Public toilets are signposted toilettes or WC. In towns, look for public toilets near the town hall, port, public squares or parking areas.
Mechanical, coin-operated toilets are free or €0.20. (Never dodge in after the previous user or you'll be doused with disinfectant!) If you exceed 15 minutes, the door automatically opens. Green means libre (available); red occupé (busy).
A few older cafes and petrol stations still have hole-in-the-floor Turkish-style toilets. Provided you hover, they're hygienic, but stand clear when flushing.