The reason why "typeerror: 'STR' object does not support item assignment" appears

1. translate

‘TypeError: ‘str’ object does not support item assignment’:

Type error ： ‘str’ Object does not support item assignment
** You can traverse the string , But every value in the string cannot be changed , Unless you assign it again

str = input()
str_length = len(str)
# Numbers 、 Strings and tuples are immutable objects 
for i in range(0,str_length):
    str[i] = int(str[i])
print(str)

practice ：

subject ：

describe
Niuniu and niumei play password games together , Niuniu, as the sender, will send a 4 Give the whole number of digits to Niu Mei , Niu Mei will crack the password after receiving it .
The solution is as follows ： Add... To every number 3 Divided by 9 Replace this digit with the remainder of , And then I will 1 Position and number 3 Bit digital switching , The first 2 Position and number 4 Bit digital switching .
Please output the password that Niu Mei cracked .
Input description ：
Enter a four digit integer .
Output description ：
Output the cracked password , In the form of four digits .
Example 1
Input ：
1234
Copy
Output ：
6745
Copy
remarks ：
Input will not have a prefix 0, But the output should be kept in front 0

Answer key ：

str = input()
count = []
for i in str:
    count.append(int(i))
for i in range(0,4):
    count[i] = count[i] + 3
    count[i] = count[i] % 9
print(count[2],end='')
print(count[3],end='')
print(count[0],end='')
print(count[1],end='')