Python Forum

So I missed the day of class where they went over rounding and I can't seem to get my code to always round to 2 decimal places.

I'm new to python and coding in general so go easy on me, i'm sure it's an easy answer but I just can't seem to figure it out and can't find a clear explanation.

Here's the part of the code I'm having troubles with:

while True:
try:
copies=float(input("Enter the number of copies to be printed --> "))
except ValueError:
print("Please enter a number.")
pass
else:
break


if copies < 100:
ppc=0.30
elif copies < 500 > 99:
ppc=0.28
elif copies < 750 > 499:
ppc=0.27
elif copies < 1001 > 749:
ppc=0.26
elif copies >1000:
ppc=0.25

total=(ppc*copies)


After I need to print the outputs of the price per copy (ppc) and the total price (ppc*copies). Easy enough until I try to make sure the values come out formatted as currecy, so 2 decimals (1.25, 1.30, etc.)

Can someone give me a hand and either write the last line of code I can evaluate or explain what I may need to do? I've looked at other examples for things like %0.2f % or whatever it is but I don't understand the lingo well enough to fit this to my assignment.

Thanks in advance.

Please put your code in Python code tags, and full error traceback message in error tags. You can find help here.

Thank you for looking but I believe I've finally figured it out. Will delete this thread if I can otherwise (since i'm new around these parts) if a mod handles that please do. Thanks!

Ok I'm glad to hear you got your solution. Thread deleting isn't necessary, don't worry. But you are welcome to post your solution in case you'd like to share.

Ok. So for the random new guy like me, here's what I figured out. I was having issues rounding float numbers to simple double digit decimals. So instead of seeing numbers like 139.89999999 or something I wanted to cut off the everything but the .89. *please note this is not rounding*

while True:
    try:
        copies=float(input("Enter the number of copies to be printed --> "))
    except ValueError:
        print("Please enter a number.")
        pass
    else:
        break
    
    
if copies < 100:
    ppc=0.30
elif copies < 500 > 99:
    ppc=0.28
elif copies < 750 > 499:
    ppc=0.27
elif copies < 1001 > 749:
    ppc=0.26
elif copies >1000:
    ppc=0.25

total=(ppc*copies)

When given certain numbers the ppc (price per copy) and total cost values were coming out weird sometimes or would end in $1.3 instead of $1.30. I wont claim to know all the details but adding {0:,.2f}".format(ppc) instead of just printing the ppc or total cuts off everything but 2 decimals. So the rest of the code is :

print("The price per copy is ${0:,.2f}".format(ppc), ".")
print("The total price is ${0:,.2f}".format(total), ".")

I know the comma after the colon adds a comma to your number every 3 digits and you can change the 2 to something else if you wanted to show more/less after the period but to be honest I don't know what the 0 before the comma and the f after 2 mean. I'll figure it out as soon as my other assignments are done and see if I can update/explain here if anyone needs/wants me to. Though I'm sure there are posts on it somewhere around here.

Thanks again.

To find out about what "f" does, you can refer this docs page.
0 is the index of item in the tuple you pass to .format(). In your case you pass it only one value (either ppc or total), so 0 just means first item, and it can even be ommitted in this case. But you could have something like .format(first_value, second_value, third_value), and in such case {2:} would mean third_value.

By the way, I believe your if/elif conditions will not work the way you want them to. For example:

elif copies < 500 > 99:

first copies < 500 is evaluated. If it is true, then 500 > 99 is evaluated, which is always true.
You probably want:

elif 99 < copies < 500:

I think it works my way, I tested a bunch of numbers and the output matches the criteria for the assignment. My brains done for the day anyway so I'll take what I get for the grade (I'm sure it's fine, he's a lazy professor.)

But I see what you're saying, I knew there was an easier/cleaner way of doing it but for whatever reason I couldn't see it at the time. I'll make sure to keep it in mind next time.

Thanks for explaining the 0. Believe it or not I actually had that stored somewhere in my mind and as soon as I read your explanation it clicked. I'll check out the link about f.

I see now, it does work indeed. However, it works mostly because (first) numbers in < conditions being checked against are in ascending order.
If the order of checking was switched in any way, it would not work anymore. In some cases it could lead to a nasty hard-to-find bug, so it is not a good habit to develop.
Also, in these cases:

elif copies < 500 > 99:
    ppc=0.28
elif copies < 750 > 499:
    ppc=0.27
elif copies < 1001 > 749:

for reason stated in last post, the second check (>) has no effect, it is always true.

I hope you get a good score on the assignment!