Question

Write a Python program that does the following:

Obtains the following input from a user:

Mileage at beginning of measurement period

Mileage at end of measurement period

Gallons of fuel consumed

Calculates and displays:

Miles driven

Miles per gallon

Kilometers driven

Liters of fuel consumed

Kilometers per liter

Also incorporate some selection structure logic into it.

If a vehicle gets less than 15 miles per gallon, display the message:

      "Your vehicle has criminally low fuel efficiency."

If it gets 15 or more but less than 20, display:

      "Your vehicle has undesirably low fuel efficiency."

If it gets 20 or more but less than 25, display:

      "Your vehicle gets barely acceptable efficiency."

If it gets 25 or more but less than 35, display:

      "Your vehicle gets high fuel efficiency."

If it gets 35 or more, display:

      "Your vehicle gets outstanding fuel efficiency."

Also incorporate repetition:

If a user enters a non-numeric values for any of the input values, display an error message informing him of his mistake and require him to re-enter the value.

If a user enters a negative numeric values for any of the input values, display an error message informing her of her mistake and require her to re-enter the value.

Test the validity of each input separately. Do not allow a user to enter data for a variable until he enters a valid value for the previous variable.

Answer 1

Program:

flag = True
mileage1 = ""
mileage2 = ""
gallon_used = ""

while flag:
    flag1 = True
    # this loop will continue until it gets correct value for mileage
    while flag1:
        mileage1 = input("Enter mileage at beginning of measurement period: ")
        # if value is not numeric this will execute
        if not mileage1.isnumeric():
            try:
                mileage1 = float(mileage1)
                if mileage1 < 0:
                    print("Enter non negative value!!")
                    continue
                flag1 = False
            except ValueError:
                print("Enter only numeric data!!")
                continue
        else:
            mileage1 = float(mileage1)
            flag1 = False

    flag1 = True
    # this loop will continue until it gets correct value for mileage
    while flag1:
        mileage2 = input("Enter mileage at end of measurement period: ")
        if not mileage2.isnumeric():
            try:
                mileage2 = float(mileage2)
                if mileage2 < 0:
                    print("Enter non negative value!!")
                    continue
                flag1 = False
            except ValueError:
                print("Enter only numeric data!!")
                continue
        else:
            mileage2 = float(mileage2)
            if mileage2 < mileage1:
                print("Mileage at end of measurement period should be greater than at the beginning of measurement period")
                continue
            flag1 = False

    flag1 = True
    # this loop will continue until it gets correct value for gallons
    while flag1:
        gallon_used = input("Enter Gallons of fuel consumed: ")
        if not gallon_used.isnumeric():
            try:
                gallon_used = float(gallon_used)
                if gallon_used < 0:
                    print("Enter non negative value!!")
                    continue
                flag1 = False
            except ValueError:
                print("Enter only numeric data!!")
                continue
        else:
            gallon_used = float(gallon_used)
            flag1 = False

    # calculating values
    miles_driven = mileage2 - mileage1
    miles_per_gallon = miles_driven / gallon_used
    kilometers_driven = miles_driven * 1.60934
    liters_used = gallon_used * 3.78541
    kilometers_per_liters = kilometers_driven / liters_used

    print("Miles driven: ", miles_driven)
    print("Miles per gallon: ", miles_per_gallon)

    # applying conditions
    if miles_per_gallon < 15:
        print("Your vehicle has criminally low fuel efficiency.")
    elif 20 > miles_per_gallon >= 15:
        print("Your vehicle has undesirably low fuel efficiency.")
    elif 25 > miles_per_gallon >= 20:
        print("Your vehicle gets barely acceptable efficiency.")
    elif 35 > miles_per_gallon >= 25:
        print("Your vehicle gets high fuel efficiency.")
    elif miles_per_gallon >= 35:
        print("Your vehicle gets outstanding fuel efficiency.")

    # printing values
    print("Kilometers driven", kilometers_driven)
    print("Liters of fuel consumed", liters_used)
    print("Kilometers per liter", kilometers_per_liters)

    # asking the user if he/she wants to continue
    print("Do you wish to continue calculating? Enter Y for YES and N for NO: ")
    cont = input()
    if cont == 'N':
        flag = False
        print("Exiting the program")

Output:

Enter mileage at beginning of measurement period: 1ab
Enter only numeric data!!
Enter mileage at beginning of measurement period: -100
Enter non negative value!!
Enter mileage at beginning of measurement period: 100
Enter mileage at end of measurement period: 50
Mileage at end of measurement period should be greater than at the beginning of measurement period
Enter mileage at end of measurement period: 260.92
Enter Gallons of fuel consumed: 90.47
Miles driven: 160.92000000000002
Miles per gallon: 1.77871117497513
Your vehicle has criminally low fuel efficiency.
Kilometers driven 258.97499280000005
Liters of fuel consumed 342.4660427
Kilometers per liter 0.7562063402206038
Do you wish to continue calculating? Enter Y for YES and N for NO:
Y
Enter mileage at beginning of measurement period: 100.4
Enter mileage at end of measurement period: 200
Enter Gallons of fuel consumed: 80
Miles driven: 99.6
Miles per gallon: 1.2449999999999999
Your vehicle has criminally low fuel efficiency.
Kilometers driven 160.29026399999998
Liters of fuel consumed 302.8328
Kilometers per liter 0.5293028496252716
Do you wish to continue calculating? Enter Y for YES and N for NO:
N
Exiting the program

Screenshots: