append 字符串到列表/字符串返回 'None' 或 'AttributeError: 'str' object 在 python 中没有属性 'append''

Question

I'm trying to add 1 word/string to the back of the sentence 'Afterall, what affects one family '.

Using the append method, it either returns 'None' if I append directly to the list or it will return an error 'AttributeError' if I append to the string. May I know how do I add the word/string to the back of the sentence?

S1 = 'Afterall , what affects one family '
Insert_String = 'member'
S1_List = ['Afterall', ',', 'what', 'affects', 'one', 'family']
print(type(S1_List))
print(type(Insert_String))
print(type(S1))

print(S1_List)
print(Insert_String)
print(S1)

print(S1_List.append(Insert_String))
print(S1.append(Insert_String))




Output

<type 'list'>
<type 'str'>
<type 'str'>
['Afterall', ',', 'what', 'affects', 'one', 'family']
member
Afterall , what affects one family 
None
AttributeErrorTraceback (most recent call last)
<ipython-input-57-2fdb520ebc6d> in <module>()
     11 
     12 print(S1_List.append(Insert_String))
---> 13 print(S1.append(Insert_String))

AttributeError: 'str' object has no attribute 'append'

Answer 1

The difference here is that, in Python, a "list" is mutable and a "string" is not -- it cannot be changed. The "list.append" operation modifies the list, but returns nothing. So, try:

S1_List.append(Insert_String)
print(S1_List)
print(S1 + Insert_String)

Answer 2

The string data type is immutable and does not have an append() method. You could try to perform string concatenation:

old_string = old_string + new_string