Python Variables

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Video Lecture

Variables:

• Variables are named locations in memory that are used to hold a value that may be modified by the program.

• A variable may take different values at different time during execution.

• A variable name must be a valid identifier, means can be a group of both letters and digits, but they have to begin with a letter or an underscore.

Variable name should not be a keyword.

To understand variable, you can assume that variable is like a container that holds data.

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Declaring Variable and Assigning Values

• In Python, You don't need to specify the type of variable because Python is a type infer language.

• You don't need to declare explicitly variable in Python. When you assign any value to the variable that variable is declared automatically.

Syntax :

variable_name = value
for e.g.

name = "prowessapps"
age  = 20
salary = 20000
tax_rate = 4.5

• As you assign value to the variable, that variable becomes of that type.

• To check the type of any variable you can use inbuilt function type ( ).

type ( ) Function :

>>> name = "prowessapps"
>>> type(name)
<class 'str'>  type of 'name' is 'string'

>>> age = 20
>>> type(age)
<class 'int'>  type of 'age' is 'int'

>>> rate = 4.5
>>> type(tax_rate)
<class 'float'>  type of 'rate' is 'float'
>>>

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Python is dynamically typed language.

Meaning of dynamically typed :

Dynamically type means you can use same variable for different value in the same program.

As per your passed value to the variable, it will become of that type.

>>> a = 20
>>> type(a)
<class 'int'>  here 'a' is 'int'

>>> a = 2.3
>>> type(a)
<class 'float'>  now 'a' is 'float'

>>> a = "Hello"
>>> type(a)
<class 'str'>  now 'a' is 'string'

Multiple Assignment

Assigning single value to multiple variables :

#script.py

x=y=z=50
print(x)
print(y)
print(z)

OUTPUT :

50
50
50

Assigning multiple values to multiple variables:

#script.py

x, y, z = 50, 2.3, "Hello"
print(x)
print(y)
print(z)

OUTPUT :

50
2.3
Hello

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