exercice 79: iterateur
exercice 81: fct amies,skeleton
exercice 81: fct amies, done
exercice 82: fonctions amies
exercice 83: class vect ok
exercice 83: class matrice ok
exercice 83: produit ok
exercie 84, setup operator = member)
exercie 84, setup operator == member)
exercie 84, setup operator != member)
exercie 84, setup all op friend && member
exercie 84, setup op + & * friend
exercice 86: skeleton
exercice 86. ok
exercice 87: skeleton
exercice 87: ouff done
exercice 87: version 2
exercice 88: correction
exercice 88: myOwn
exercice 89: my work