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，我们需要设置一个1到3之间的难度，但是当有人输入一个错误的数字，他们会得到一行，说请在1和3之间选择，但问题应该重复本身，现在代码刚刚结束，当你输入一个错误的数字。你知道吗

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

“当难度在0以下，难度在4以上时，永远不可能是真的，因为没有同时小于0和大于4的数字。格式化条件最可读的方法是使用range：

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))

也可以省略if，因为循环已经确保值在有效范围内；无需再次检查。你知道吗

Answer 2

while循环0 > difficulty > 4从不执行，因为该条件的计算结果总是False，因为0 > 4是False，因此我将while循环重构为while difficulty > 4 or difficulty < 0:，它检查难度是小于0还是大于4，也正如@deceze指出的那样，if是不需要的，因为该条件只在我们确保难度介于0和4之间，不包括0和4

所以答案变为

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))

输出看起来像

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，这实际上可以通过while not 0 < difficulty < 4:实现

然后答案将改为

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 3

试着这样做：

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