the function miroir (in french ) it means "mirror" , the major idea is to permute the first caractere with the last using an auxilary variable (aux) the the 2nd character with the penultimate one and so on . we made a call to the function (compte) which counts the length of the string . As you can see clearly , I substruct 1 from the equation k = compte(s)-1 ; to get rid of the EOF caractere which