尽管使用 for 循环添加元素，为什么我的列表仍然为空

Question

I'm trying to do the following: - check if the element from one list exists in another list. If so, do nothing, if not append it to that list.

Simplefied example code:

x=[1,2,3]
y=[2,3,4]

for item in x:
    if item in y=='False':
        y.append(item)
    else:
        continue
print(y)

Unfortunately it does not work and as a beginner I'm not sure why. Any thoughts?

Answer 1

The reason why your code doesn't work, is that the statement:

if item in y=='False':

checks if the boolean answer of the condition

item in y

is equal to the string 'False' for it to trigger the if block.

---

Based on your question, the code correction should be:

if item not in y:
    y.append(item)

In the above example, the if block is entered when there is an item in x that is not present in list y

Answer 2

x=[1,2,3]
y=[2,3,4]

for item in x:
    if item not in y:
        y.append(item)
    else:
        continue
print(y)

Gives:

[2, 3, 4, 1]

Answer 3

You should use:

x=[1,2,3]
y=[2,3,4]

for item in x:
    if item not in y:
        y.append(item)
    else:
        continue
print(y)

The line: if item in y=='False': will never be true because if an item is not in y, it will return the boolean False, not the string 'False'