重复一个问题，直到得到一个好答案

Question

我正在为学校做一个小项目，我们需要在1到3之间设置一个困难，但是当有人输入一个错误的号码时，他们会收到一条线，上面写着请在1到3之间选择，但是这个问题应该重复一遍，现在当你输入一个错误的号码时，代码就会终止。

difficulty = int(input("Difficulty: "))

while 0 > difficulty > 4:
    print("This is not a valid difficulty, please choose 1, 2 or 3")
    difficulty = int(input("Difficulty: "))

if 0 < difficulty < 4:
    print("The playing board was created with difficulty: " + str(difficulty))

Answer 1

when循环0 > difficulty > 4从不执行，因为该条件总是计算为False，因为0 > 4是False，因此我会将when循环重构为while difficulty > 4 or difficulty < 0:，这将检查困难是否小于0，还是大于4，也像@deceze指出的那样，if不需要，因为只有当我们确保我们的困难在0到4之间(不包括0和4)时，才需要if。

所以答案改变为

difficulty = int(input("Difficulty: "))

#Check if difficulty is less than 0, or greater than 4
while difficulty < 0 or difficulty > 4:
    print("This is not a valid difficulty, please choose 1, 2 or 3")
    difficulty = int(input("Difficulty: "))

print("The playing board was created with difficulty: " + str(difficulty))

输出将类似于

Difficulty: -1
This is not a valid difficulty, please choose 1, 2 or 3
Difficulty: 5
This is not a valid difficulty, please choose 1, 2 or 3
Difficulty: 2
The playing board was created with difficulty: 2

编写while循环的另一种方法是，我们需要确保如果输入小于0或大于4，我们希望继续运行循环，这实际上可以由while not 0 < difficulty < 4:实现。

然后答案将更改为

difficulty = int(input("Difficulty: "))

#Check if difficulty is less than 0, or greater than 4
while not 0 < difficulty < 4:
    print("This is not a valid difficulty, please choose 1, 2 or 3")
    difficulty = int(input("Difficulty: "))

print("The playing board was created with difficulty: " + str(difficulty))

Answer 2

就像这样：

difficulty = int(input("Enter input :"))
while difficulty<1 or difficulty>3:
  difficulty = int(input("Enter input between 1 and 3 :"))
print("correct input:",difficulty)

Answer 3

“困难小于0，困难大于4”不可能是真的，因为没有一个同时小于0和大于4的数字。

difficulty = int(input("Difficulty: "))

while difficulty not in range(1, 4):
    print("This is not a valid difficulty, please choose 1, 2 or 3")
    difficulty = int(input("Difficulty: "))

print("The playing board was created with difficulty: " + str(difficulty))

您还可以省略if，因为循环已经确保该值在有效范围内；无需再次检查。