为什么我的真实陈述不起作用？

Question

这是一本字典:

Vocab ={'Adherent' : " supporter; follower.",
'Incoherent' : "without logical or meaningful connection; disjointed; rambling",
'Inherent' : "existing in someone or something as a permanent and inseparable element, quality, or attribute"}

我在循环中创建了一组简单的if语句:

while 1:
    x = Vocab[random.choice(Vocab.keys())]
    print x
    t1=raw_input("What word matches this definition?: ")
    if t1 in Vocab == True:
        if Vocab[t1] == x:
            print "That's correct!"
        elif Vocab[t1] != x:
            print "That's wrong!"
    else:
        print "That's not a word!"
    raw_input("Hit 'enter': ")

出于某些奇怪的原因,当用户输入字典中的键时,代码输出:

"That's not a word"

为什么'== True'的if语句不起作用？

Answer 1

您不需要使用if t1 in Vocab == True,只需使用if t1 in Vocab.

问题是操作数优先级.在==超过了优先级in,所以当你写if t1 in Vocab == True的Python解释为if t1 in (Vocab == True).

要解决优先级问题,可以这样编写:if (t1 in Vocab) == True:,但是再次没有必要比较结果t1 in Vocab是否True,简单使用:

if t1 in Vocab: