Python money denomination loop does not work on decimal

Question

I am learning python and I what I need to achieve is to count how many denominations of 1000, 500, 200, 100, 50, 20, 10, 5, 1 , 0.25, 0.01 count base on my input data of 1575.78.This specific code bums me out.

def withdraw_money():
denoms = (1000, 500, 200, 100, 50, 20, 10,5,1,.25,0.01)
while True:
    try:
        withdraw = 1575.770
        break
    except Exception as e:
        print('Incorrect input: %s' % e)
    

print("Here is the bill breakdown for the amount input")
for d in denoms:
    count = withdraw // d
    print('P%i = %i' % (d, count))
    withdraw -= count * d
 

withdraw_money()

My current output is:

Here is the bill breakdown for the amount input

P1000 = 1
P500 = 1
P200 = 0
P100 = 0
P50 = 1
P20 = 1
P10 = 0
P5 = 1
P1 = 0
P0.25 = 3
P0.01 = 2

which is wrong because the P0.01 = 2 is suppose to be P0.01 =3.

However this code is correct when running whole numbers like 1500, or 20 but large number with decimal it get wrong on the 0.01 denomination count.

Asked By: MiksMeister

||

Source

Answer 1

You can use f string here like below

def withdraw_money():
    denoms = (1000, 500, 200, 100, 50, 20, 10, 5, 1, .25, 0.01)
    while True:
        try:
            withdraw = 1575.770
            break
        except Exception as e:
            print('Incorrect input: %s' % e)

    print("Here is the bill breakdown for the amount input")
    for d in denoms:
        count = withdraw // d
        print(f'P{d} = {count:0.0f}')
        withdraw -= count * d


withdraw_money()

Output:

Here is the bill breakdown for the amount input
P1000 = 1
P500 = 1
P200 = 0
P100 = 0
P50 = 1
P20 = 1
P10 = 0
P5 = 1
P1 = 0
P0.25 = 3
P0.01 = 1

Answered By: Deepan

Answer 2

After debugging the code, I found the error. Using round() solve the problem.

def withdraw_money():
    denoms = (1000, 500, 200, 100, 50, 20, 10,5,1,0.25,0.01)
    while True:
        try:
            withdraw = 1575.77
            break
        except Exception as e:
            print('Incorrect input: %s' % e)
        
    print("Here is the bill breakdown for the amount input")
    for i in range(len(denoms)):
        if denoms[i] != 0.01: count = withdraw // denoms[i]
        else: count = withdraw / denoms[i]
        print(f'P{denoms[i]} = {count:0.0f}')
        withdraw = round(withdraw % denoms[i],2)
     

withdraw_money()

Answered By: Muntasir Aonik

Python money denomination loop does not work on decimal

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