为什么这个 python while 循环没有结束? [英] Why is this python while loop not ending?

问题描述

我想知道为什么这段代码似乎无限循环?逻辑，while not False = while True，而这个 True 指的是 100 <0 这是错误的，因此它应该执行打印语句，对吗?为什么它会卡在循环中呢..?

I am wondering why this code seems to loop infinitely? The logic, while not False = while True, and this True is referring to 100 < 0 which is false, hence it should execute the print statement instead, right? Why is it stuck in the loop then..?

num = 100
while not False:
    if num < 0:
        break
print('num is: ' + str(num))

推荐答案

简短回答:由于以下内容不正确，您的 if 子句的内容将不会被评估，因此 不执行 break.

Short answer: Since the following is not true, the contents of your if clause will not be evaluated, hence the break is not performed.

if num < 0:

真正运行的是以下内容:

All that is really running is the following:

num = 100
while not False:
    if num < 0: #False
        #what is here is unimportant, since it will never run anyway.

...或者一路"简化它，这就是你正在做的:

...or to simplify it "all the way", this is what you're doing:

while true:
    if false:
        break

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