All fundamental data types (int, float, complex, bool, str) are immutable. i.e. once we creates an object, we cannot perform any changes in that object. If we are trying to change then with those changes a new object will be created. This non-changeable behaviors’ is called immutability.
In python if a new object is required, then PVM wont create object immediately. First it will check is any object available with the required content or not. If available then existing object will be reused. If it is not available then only a new object will be created. The advantage of this approach is memory utilization and performance will be improved.
But the problem in this approach is, several references pointing to the same object, by using one reference if we are allowed to change the content in the existing object then the remaining references will be effected. To prevent this immutability concept is required. According to this once creates an object we are not allowed to change content. If we are trying to change with those changes a new object will be created.

Example 1

Python

num1 = 10
num2 = 10

print(num1 is num2)
print(id(num1))
print(id(num2))

Output

PowerShell

True
3228203248208
3228203248208

Example 2

Python

bool1 = True
bool2 = True

print(bool1 is bool2)
print(id(bool1))
print(id(bool2))

Output

PowerShell

True
3228203243456
3228203243456

Example 3

Python

str1 = "ajay"
str2 = "ajay"

print(str1 is str2)
print(id(str1))
print(id(str2))

Output

PowerShell

True
3228203243123
3228203243123

Reusability of int value applicable only for 0-256 value.

Example

Python

num1 = 256
num2 = 256

print(num1 is num2)
print(id(num1))
print(id(num2))

Output

PowerShell

False
3228205754736
3228205754768

Reusability of object not allowed to float and complex number.

Example

Python

com1 = 10+5j
com2 = 10+5j

print(com1 is com2)
print(id(com1))
print(id(com2))

Output

PowerShell

False
3228205754836
3228205754236

Escape Characters

In String literals we can use esacpe characters to associate a special meaning.
The following are various important escape characters in python.
1. \n ==> New Line
2. \t ==> Horizontal tab
3. \r ==> Carriage Return
4. \b ==> Back space
5. \f ==> Form Feed
6. \v ==> Vertical tab
7. \’ ==> Single quote
8. \” ==> Double quote
9. \\ ==> back slash symbol

Example

Python

str1 = "ajay\nshukla"
print(str1)
            
str2 = "ajay\tshukla"
print(str2)

str3 = "this is \" symbol"
print(str3)

Output

PowerShell

ajay
shukla
ajay	shukla
this is " symbol

Constants

Constants concept is not applicable in python. But it is convention to use only uppercase characters if we don’t want to change value.

Python

MAX_VALUE = 10
print(MAX_VALUE)

Output

PowerShell

It is just convention but we can change the value.

Ungraded Questions

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