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Variables

Are containers for storing data values

Python has no command for declaring a var

Var is created the moment first assign a value to it

Vars don’t need to declared with any particular type, and can even change type after they have been set

String var can be declared either by using single or double quotes

x = 5		# x is of type int
y = “Hello”
print(x)	# output 5
x = “3”		# x is now of type str
print(x)	# output “3”
x = str(x)	# If you want to specify the data type of a var, this can be done with casting
print(x)	# output 3
print(type(x))	# output int, you can get the data type of a var with the type() func

Variable names

case-sensitive

Must start with a letter or the underscore character

Can’t start with a number

Can only contain alpha-numeric characters and underscores

Assign Multiple

Python allows to assign values to multiple vars in one line

x,y,z = “I”, “am”, “spongebob”	# Make sure the number of vars matches the number of values
print(z)		# output “spongebob”

Unpack a Collection

Python allows to extract the values into var

friends = [“Patrick”, “Squidward”, “Gary”, “Sandy”]
a,b,c,d = friends
print(a)	# output “Patrick”

Global

Var that are created outside of a func are known as global var

Global var can be used by everyone, both inside of func and outside

x = “awesome”
def func():
print(“Python is ” + x)
func()		# output “Python is awesome”

If you create a var with the same name inside a func, this var will be local, and can only be used inside the func

The global var with the same name will remain as it was, global and with the original value

def func2():
x = “pretty”
print(“Python is ” + x)
func2()		# output “Python is pretty”

# Can create a global var inside a func using `global`
def func3():
global x
x = “fantastic”
func3()
print(“python is ” + x)		#output “Python is fantastic”

Data type

Text : str

Numeric : int, float, complex

Sequence : list, tuple, range

Mapping : dict

Set : set, frozenset

Boolean : bool

Binary : bytes, bytearray, memoryview