python - 无法获取返回 false 的函数？

Question

我正在做这个练习:

Write a function is_member() that takes a value (i.e. a number, string, etc) x and a list of values a, and returns True if x is a member of a, False otherwise. (Note that this is exactly what the in operator does, but for the sake of the exercise you should pretend Python did not have this operator.)

我写了这个函数:

def isMember(value, list):
  for element in list:
    if(element == value):
      return True
    else:
      return False

myList = ["a","b","c",1,2,3]

print(isMember("a",myList)) #Returns True; correct
print(isMember(3,myList)) #Returns False; why the heck?

Answer 1

您需要将 return False 移出循环:

def isMember(value, list):
    for element in list:
        if(element == value):
            return True
    return False

按照目前的方式，如果 value 不是第一个 项，isMember 将返回 False在 列表 中。此外，您应该将列表变量的名称更改为 list 以外的名称，即 built-in function in Python。 .