'''lecture_20_while_miles.py
Use a while loop to get mileage from trips. Loop sentinel is a negative milage (invalid entry)
Goal: Compute the total number of miles across all trips and average trip miles
UPDATE 1: Add break statement if sentinel is negative
UPDATE 2: Introduce increment operator
Oliver W. Layton
CS 151: Computational Thinking: Visual Media
Spring 2021
'''
# Declare variables for number of trips that are entered and total miles entered
totalMiles = 0
numTrips = 0

# Get user input
print('Enter a negative number to stop entering trip mileage.')
currMiles = int(input('Please enter the number of miles you traveled in a trip: '))

# Get data while the user entry is valid (>0), first updating the mileage total and number of trips
while currMiles >= 1:  # currMiles > 0 also works, but currMiles >= 1 is ok since we're assuming an int
    # numTrips = numTrips + 1
    # totalMiles = totalMiles + currMiles

    # alternative to the 2 lines above
    numTrips += 1
    totalMiles += currMiles

    currMiles = int(input('Please enter the number of miles you traveled in a trip: ')) 

# Compute the average number of miles across all trips
avgMiles = totalMiles / numTrips

# Print number of total miles and total numebr of trips
print('You traveled', totalMiles, 'miles over', numTrips, 'trips')

# Print number of average number of miles
print('Your average number of miles per trip was', avgMiles)