public float Retrait(float montant)
 {
     if (montant <= this.Solde)
     {
         Transaction1 tr1bis = new Transaction1
         {
             Montant = montant,
             Date    = DateTime.Now
         };
         //this.ListeTransactions[this.NombreTransaction] = tr1bis;
         this.NombreTransaction++;
         this.ListeTransactions1.Add(tr1bis);
         this.Solde -= montant;
         return(this.Solde);
     }
     else
     {
         throw new Exception("Transaction impossible");
     }
 }
        public float Depot(float montant)
        {
            /* Méthode 1
             * Transaction tr = new Transaction(montant, DateTime.Now);
             *
             * Méthode 2
             * Transaction1 tr1 = new Transaction1();
             * tr1.Montant = montant;
             * tr1.Date = DateTime.Now;
             *
             * Méthode 3
             */
            Transaction1 tr1bis = new Transaction1
            {
                Montant = montant,
                Date    = DateTime.Now
            };

            //this.ListeTransactions[this.NombreTransaction] = tr1bis;
            this.NombreTransaction++;
            this.ListeTransactions1.Add(tr1bis);
            this.Solde += montant;
            return(this.Solde);
        }