# class_average_sentinel.py
"""Class average program with sentinel-controlled iteration."""

# initialization phase
total = 0  # sum of grades
grade_counter = 0  # number of grades entered

# processing phase
grade = int(input('Enter grade, -1 to end: '))  # get one grade

while grade != -1:
    total += grade
    grade_counter += 1
    grade = int(input('Enter grade, -1 to end: '))

# termination phase
if grade_counter != 0:
    average = total / grade_counter
    print(f'Class average is {average:.2f}')
else:
    print('No grades were entered')

##########################################################################
# (C) Copyright 2019 by Deitel & Associates, Inc. and                    #
# Pearson Education, Inc. All Rights Reserved.                           #
#                                                                        #
# DISCLAIMER: The authors and publisher of this book have used their     #
# best efforts in preparing the book. These efforts include the          #
# development, research, and testing of the theories and programs        #
# to determine their effectiveness. The authors and publisher make       #
# no warranty of any kind, expressed or implied, with regard to these    #
# programs or to the documentation contained in these books. The authors #
# and publisher shall not be liable in any event for incidental or       #
# consequential damages in connection with, or arising out of, the       #
# furnishing, performance, or use of these programs.                     #
##########################################################################
