Python简介：如何使用while循环获得最大值？

编写一个程序，提示用户输入1到20之间的数字，直到遇到数字20为止。不包括20，计算最大值

有人能帮我写个代码吗

inp = 0
x = 9999
while inp != 20:
    inp = int(input("Please enter a number from 1 to 20 (20 to stop): "))
    print(inp)
    if inp != 20:          

print("the maximum value is", inp)

---

我被卡住了

您的思路是正确的，但是您需要一个单独的变量来容纳最大的数字——您不能为此重用输入变量

另外，由于您已经在检查循环中的输入是否为20，因此在while条件下也检查相同的内容是重复的。只需使用

，而使用True

# keep track of the largest number entered
largest = 0

# loop forever
while True:
    # ask for input
    inp = int(input("Please enter a number from 1 to 20 (20 to stop): "))

    # if 20 was entered, quit the loop
    if inp == 20:
        break

    # if the input is larger than the largest number entered so far, save it as the largest
    if inp > largest:
        largest = inp

print("The largest number was", largest)

---

一个相当简单的解决方案

prompt = "Please enter a number from 1 to 20 (20 to stop): "

# stores the numbers that were inputted
numbers = []

number = int(input(prompt))

# keeps asking for input as long as number inputted, is not 20
while number != 20:
    numbers.append(number)
    number = int(input(prompt))

# gets the max value from the list, and prints it
print("the maximum value is", max(numbers))

---

拥有哨兵是iter的一个很好的用例：

max(iter(lambda: int(input("Please enter a number from 1 to 20 (20 to stop): ")), 20))

演示：

>>> max(iter(lambda: int(input("Please enter a number from 1 to 20 (20 to stop): ")), 20))
Please enter a number from 1 to 20 (20 to stop): 4
Please enter a number from 1 to 20 (20 to stop): 12
Please enter a number from 1 to 20 (20 to stop): 7
Please enter a number from 1 to 20 (20 to stop): 20
12