Public toilets, signposted WC or toilettes, are not always plentiful in France, especially outside the big cities.
Love them (as a sci-fi geek) or loathe them (as a claustrophobe), France's 24-hour self-cleaning toilets are here to stay. Outside Paris these mechanical WCs are free, but in Paris they cost around €0.50 a go. Don't even think about nipping in after someone else to avoid paying unless you fancy a douche (shower) with disinfectant. There is no time for dawdling either: you have precisely 15 minutes before being (ooh-la-la!) exposed to passers-by. Green means libre (vacant) and red means occupé (occupied).
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 France'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.