python session day 3 at payilagam

data type - mentioning what type of data is it
name = 'raja' -> string data type
num = 1 -> integer data type
num = 2.2 -> float data type

boolean data type : True or False
ex: raining = False

in python it boolean data type is denoted as bool.
integer and float adds negative num also.

address = '5/2A, South Street, Madurai.'

Here,
address -> variable
= -> assignment operator
'5/2A,South Street, Madurai,' -> values

reference variable - Identifiers(The name given for a variable)

How can we write identifiers
1) Meaning full names
2) No space allowed
3) Numbers are allowed, but not in first.
4) No special character is allowed, except _ and $

Return data types :
From the previous day, we are going to define a function

def add(no1, no2):
    print(no1+no2)


def subtract(no1, no2):
    print(no1-no2)


def multiply(no1, no2):
    print(no1*no2)


def divide(no1,no2):
    print(no1/no2)

no1 = 10
no2 = 12
add(no1, no2)
subtract(no1, no2)

whatever we are calling it only derived as output.

def add(no1, no2):
    print(no1+no2)
    return no1+no2

def subtract(no1, no2):
    print(no1-no2)
    return no1-no2

def multiply(no1, no2):
    print(no1*no2)


def divide(no1,no2):
    print(no1/no2)

no1 = 10
no2 = 12
r1 = add(no1, no2)
r2 = subtract(no1, no2)
multiply(r1,r2)

in this case we are returned the values of the function.
so it multiplies lies (the answer of add * the answer of subtract)

type function is used to denote which data type is used.

print(type(subtract(100,50)))
print(type(multiply(10,20)))

In this case the first on gives answer as 50 and it gives the data type as int.

but in case of multiply the value has not returned so, it simply says none type.