Q. Is French hair cut allowed in islam?
A. Sadly, I am not familiar with distinguishing factors pertaining to haircuts. More so, I am unfamiliar with the technical aspects pertaining to a German, French or an African haircut.
However Islam stresses woman are to grow their hair. For medical reasons they can have it trimmed. Under normal conditions, the most a woman can cut her hair is to straighten it at the bottom. This would be to bring neatness to its length. Such cutting would not involve more then an inch.
As for men, if men chose to keep their hair short, then it must be cut in an even length. Rasulullah (sallallaahu alayhi wa sallam) also shaved his blessed hair. Should a man wish to keep what is known as the Zulfa, then they can grow their hair until it reaches the ear lobe, or hair can grown to the length between ear lobe and shoulder. Finally, a zulfa grooming can include the length up to the shoulders.
In all situations the hair should be well oiled and neatly maintained. Islam does not have much regard for a cannibalistic look.
Allah Certainly Knows Best.