Immutable vs Mutable types

Question

I\'m confused on what an immutable type is. I know the float object is considered to be immutable, with this type of example from my book:

class         


        

Answer 1

A class is immutable if each object of that class has a fixed value upon instantiation that cannot SUBSEQUENTLY be changed

In another word change the entire value of that variable (name) or leave it alone.

Example:

my_string = "Hello world" 
my_string[0] = "h"
print my_string 

you expected this to work and print hello world but this will throw the following error:

Traceback (most recent call last):
File "test.py", line 4, in 
my_string[0] = "h"
TypeError: 'str' object does not support item assignment

The interpreter is saying : i can't change the first character of this string

you will have to change the whole string in order to make it works:

my_string = "Hello World" 
my_string = "hello world"
print my_string #hello world

check this table:

source