Python ValueError：以 10 为基数的 int() 文字无效：

Question

I am trying to write a program to do some simple power usage and cost calculations, the logic is correct and the algorithm works for VB but I want to use Python. Being new to Python I am a little confused as to what I am missing, the code is below. I have used some conventions here to help me understand what is happening

IntWatts = input ("What is the Watt rating? ")
IntHoursOfUse = input ("How many hours is the device on for? ")
IntTariff = input ("What is the Tariff in cents? ") 

IntEnergyRating = int(IntWatts)/1000
IntUsageKWH = int(IntEnergyRating) * IntHoursOfUse
IntCostInCents = IntUsageKWH * int(IntTariff)
IntCostInDollars = float(IntCostInCents) / 100 

print('the Cent cost is :',IntCostInCents)
print("the Dollar cost is ;", IntCostInDollars)enter code here

I have been using the inputs of Watts 240 HoursOfUse 5 Tariff 34.1

Thanks

Answer 1

As to why the error is happening, it is simply a matter of typecasting the wrong variable, note the example below.

watts = input('What is the Watt rating?')
hours_of_use = input('How many hours is the device on for?')
tariff = input('What is the Tariff in cents?')

energy_rating = int(watts) / 1000
usage_kwh = energy_rating * int(hours_of_use)                                     
cost_in_cents = usage_kwh * int(tariff)
cost_in_dollars = cost_in_cents / 100

print('The cent cost is :', cost_in_cents)
print('The dollar cost is :', cost_in_dollars)

This code should produce the results you are looking for. As to what some of the problems are here.

A few things to note, you only need to cast the input() values here since they are coming in as strings and need to be interpreted in your program as integers.

In Python there are two forms of division / which results in expected results according to how we as humans learn math, and // which will floor your result; this is why you do not need to cast to floats.

There are many pythonic things here to take away as you learn this language, while I won't go into great depth, do note the naming conventions. Python variables are typically _ delimited, lowercase and self-documenting. Additionally it is considered fairly poor practice to label variables with type, this is an old convention that has fallen out of practice.

For additional reading on Python, check out the coding guidelines: https://web.archive.org/web/20111010053227/http://jaynes.colorado.edu/PythonGuidelines.html#module_formatting

Answer 2

you need to type-cast IntHoursOfUse to int while initializing IntUsageKWH as:

#                                  v  Type casting this to int()
IntUsageKWH = IntEnergyRating * int(IntHoursOfUse)
#             ^ No need to type-cast this as you are already doing it in previous line

Answer 3

I needed to change the inputs to be

IntWatts = int(input ("What is the Watt rating? "))
IntHoursOfUse = int(input ("How many hours is the device on for? "))
IntTariff = float(input ("What is the Tariff in cents? "))

and then remove all other int/float commands

Thanks for the help