Mutable and Immutable Object’s
Mutable Object : The value of mutable object can be modified in place after it’s creation.
ex: list, dict, set, byte array, user defined classes.
Immutable Object: The value of immutable object cannot be changed.
ex: int, float, long, complex, string, tuple, bool.
“int” Data Type:
The python implementation first load an array of integer between -5 to 256.
Hence variable referring to an integer within the range would be pointing to the same object that already exists in memory.
1) a = 256
b = 256
a is b ?
2) a = 257
b = 257
a is b ?
3) z = 3 + True
print(z)
print(type(z))
“float” Data Type:
This are immutable data types.
Floats may also be in scientific notation, with E or e indicating the power of 10 (2.5e2 = 2.5 x 102 = 250).
1) x = 4.5
y = 2.5
z = x + y -2.5
2) x = 10
y = 5
z = x + y - 5
“string” Data Type:
Sequence of collection of character.
The python string can be represented using:
1) Single Quote (‘ ’)
2) Double Quote (“ ”)
3) Triple Quote (”” ’’’)
Exception with immutable object:
1) a = “Python is Cool !”
b = “Python is Cool !”
2) a = “python”
b = “python”
This is a result of string interning, which allows 2 variable to refer to the same string object.
One can forcibly intern string by calling sys.intern() function.
“bool” Data Type:
True Values:
- Any string is True, except empty strings.
- Any number is True, except 0.
- Any list, tuple, set, and dictionary are True, except empty ones
False Values:
- In fact, there are not many values that evaluates to False, except empty values, such as (), [], {}, "", the number 0, and the value None. And of course the value False evaluates to False.
“complex” Data Type:
Complex numbers are written in the form, x+yj, where x is real part and j is the imaginary part.
Complex number by using complex() function.
