检查python列表的内容

Question

Using python 2.7.4

Lets say I have a list

list = ['abc', 'def']

I want to find if it contains certain things. So I try:

 [IN:] 'abc' in list
[OUT:] True
 [IN:] 'def' in list
[OUT:] True
 [IN:] 'abc' and 'def' in list
[OUT:] True

But when I list.pop(0) and repeat that last test:

 [IN:] 'abc' and 'def in list
[OUT:] True

Even though:

list = ['def']

Anybody know why?

Answer 1

That's because:

abc' and 'def' in list

is equivalent to:

('abc') and ('def' in list) #Non-empty string is always True

Use 'abc' in list and 'def' in list or for multiple items you can also use all()

all(x in list for x in ('abc','def'))

_{Don't use list as a variable name, it's a built-in type.}