错误使用“或”运算符

问题描述

如果用户输入的不是“ Y”或“ N”，则该代码应返回false。当用户键入“ Y”时，它结束循环，但是当键入“ N”时，它仍继续循环。如何纠正？

# Ask if they want to continue
    while True:
        
        noOrYes = input(f"Do you want to continue? (Y/N)")
        if not noOrYes == "Y" or noOrYes == "N":
            print("Sorry,I didn't understand that.")
            #better try again... Return to the start of the loop
            continue
        else: 
            #firstName & lastName was successfully parsed!
            #we're ready to exit the loop.
            print(f"break")
            break

解决方法

类似于数学运算和PEMDAS，布尔运算符（and，or，==）都有一个“ order of operations”。现在，您要问两个问题：

noOrY是否等于Y？

noOrYes是否等于N？

使用括号固定操作顺序。 if not (noOrYes == "Y" or noOrYes == "N")

,

您可以改为这样做：

while True: 
    noOrYes = input(f"Do you want to continue? (Y/N)")

    if noOrYes == "Y":
        break
    
    else : 
        print("Sorry,I didn't understand that.")

,

而不是询问“如果不是”。以下代码处理的每个输入都不是“是”或“否”的某些变体（例如，“是”，“不”等）。

# Ask if they want to continue
while True:
    noOrYes = input(f"Do you want to continue? (Y/N)")
    if noOrYes.lower().startswith('y'):
        #User gave a proper response
        #we're ready to exit the loop.
        break
    elif noOrYes.lower().startswith('n'):
        #User gave a proper response,#we're ready to exit the loop.
        break
    else: 
        print("Sorry,I didn't understand that.")
        #Better try again... returning to the start of the loop
        continue