Python: Variables

Hi All,
Today we are going to learn python variables.

VARIABLES

1. Commonly variables are keep some value like str, int etc.
2. Python didn't use any command for declare variable, when the value 3. assigned first that moment variables are created and case sensitive.
3. Variables don't need to be declared with any particular type and can even change the type after they set.

a=1         # variable as int
b="aravin"  # variable as string
x=5         # First assign the int value to X
x='aravin'  # Later assign the str value to X
print(x)    # o/p aravin, recently assign value to use same variable.

Case Sensitive

a=100
A='India' # a will not overwrite to A both are diff.
print(a)
print(A)

To get Variable type

var=100
mvar='Hello'
print(type(var))

Rule for Create Variable

1. Variable name should be start with char or underscore char.
2. Should not be start with numbers.
3. Should not be any of python key word.

Ex:
Proper Name:
my_variable_name = "Aravin" #snake type
myVariableName = "Aravin" #Camel type
MyVariableName = "Aravin" #Pascal type
myvarname = "Aravin"
_myvarname = "Aravin"
myvar_name = "Aravin"
myvar21 = "Aravin"

Improper Name:
2myVar = "Hello"
my-var = "Hello"
my var = "Hello"

To assign multiple values to multiple variable

a,b,c = 5,"aravin","DB"

One value to multiple variable

a = b = c = "Apple"

To unpack a collection

myVar = ["var1","var2","var3"]
a,b,c = myVar
print(myVar)
print(b)

Global Variable

1. To be created outside the function called global variable Or created with global keyword.
2. Global variable can be used by everyone both inside and outside function

Ex:

Created outside the function

a = "python"
def myfunc():
  print("Hello " + a)
myfunc()

Variable created inside the function, with same name of global

a = "python"
def myfunc():
  a = "python"
  print("Hai " + a)
myfunc()
print("Hello " + a)

Create global variable by use global keyword inside the function

def myfunc():
  global a
  a = "python"
myfunc()
print("Hello " + a)

Change global variable value inside the function

a = "python"
def myfunc():
  global a
  a = "Python"
myfunc()
print("Hai " + x)