Python问题——AttributeError: 'NoneType' object has no attribute 'append'

python提示AttributeError: 'NoneType' object has no attribute 'append'

 

 

Python问题——AttributeError: 'NoneType' object has no attribute 'append'

f=open("data.csv")
for line in f:
    line = line.strip("\n")
    ls = line.split(",")
    lt=[]
    for word in ls:
        word=word.strip()
        lt=lt.append(word)

    print(",".join(lt))
f.close()

把lt= lt.append(word)改为lt.append(word)后问题解决。

原因：append会修改a本身，并且返回None。不能把返回值再赋值给a。