Python程序计算变化

Question

该程序计算硬币的存量变化。 然后，它要求购买物品的价格。 如果输入价格，它将提示您输入美元并打印硬币找零。

我在下面尝试了以下代码：

quarters = 10
dimes = 10
nickels = 10
pennies = 10

quarters_spent = 0
dimes_spent = 0
nickels_spent = 0
pennies_spent = 0

print("\nWelcome to change-making program.")
print("\nStock: {} quarters, {} dimes, {} nickels, and {} pennies".format(quarters, dimes, nickels, pennies))
in_str = input("Enter the purchase price (xx.xx) or 'q' to quit: ")
while in_str.lower() != 'q':
    dollar_str, cents_str = in_str.split(".")

in_int = int(float(in_str)*100)

if in_int < 0:
    print("Error: purchase price must be non-negative.")
    in_str = input("\nEnter the purchase price (xx.xx) or 'q' to quit: ")
if in_int > 0:
    payment = input("\nInput dollars paid: ")
    payment_int = int(float(payment)*100)

if payment_int < in_int:
    print("Error: print again.")
    payment = input("\nInput dollars paid: ")
    payment_int = int(float(payment)*100)
    change = payment_int - in_int

if change == 0:
    print("No change.")

while change >= 25 and quarters > 0:
    change -= 25
    quarters_spent += 1
    quarters -= 1

while change >= 10 and dimes > 0:
    change -= 10
    dimes_spent += 1
    dimes -= 1

while change >= 5 and nickels > 0:
    change -= 5
    nickels_spent += 1
    nickels -= 1 

while change >= 1 and pennies > 0:
    change -= 1
    pennies_spent += 1
    pennies -= 1

if quarters == 0 and dimes == 0 and nickels == 0 and pennies == 0:
    print("Error: ran out of coins.")
    quit()

print("\nCollect Payment Below:")
  if quarters > 0:
    print(quarters_spent, "quarters")
if dimes > 0:
    print(dimes_spent, "dimes")
if nickels > 0:
    print(nickels_spent, "nickels")
if pennies > 0:
    print(pennies_spent, "pennies")

print("\nStock: {} quarters, {} dimes, {} nickels, and {} pennies".format(quarters, dimes, nickels, pennies))

in_str = input("\nEnter the purchase price (xx.xx) or 'q' to quit: ")

输入：1.5 2 q我期望输出：8 q，10 d，10 n和10 p

实际结果：该程序未运行，要求输入“输入购买价格（xx.xx）或'q'退出：”，然后什么也没有发生。 询问该短语后，该程序根本不会运行。

Answer 1

如果输入不是Q或q循环将是无限的：

while in_str.lower() != 'q':
    dollar_str, cents_str = in_str.split(".")

修复：还允许循环内的其他可接受输入或重新请求输入。