Python Text Processing - String Immutability

In python, the string data types are immutable. Which means a string value cannot be updated. We can verify this by trying to update a part of the string which will led us to an error.

Checking Immutability of a String

main.py

# Can not reassign 
t= "Tutorialspoint"
print(type(t))
t[0] = "M"

Output

When we run the above program, we get the following output

<class 'str'>

Warnings/Errors:
Traceback (most recent call last):
  File "/home/cg/root/31c1433c/main.py", line 4, in <module>
    t[0] = "M"
    ~^^^
TypeError: 'str' object does not support item assignment

Checking Memory Location of Letters of a String

We can further verify this by checking the memory location address of the position of the letters of the string.

main.py

x = 'banana'

for idx in range (0,5):
    print(x[idx], "=", id(x[idx]))

Output

When we run the above program we get the following output. As you can see above a and a point to same location. Also N and N also point to the same location.

b = 11817208
a = 11817160
n = 11817784
a = 11817160
n = 11817784