Basic Data types in Python

Integers

In [15]:
#Assigning a value to variable

x=1
In [11]:
#Print function is used to print the object

print(x)

1
In [12]:
#Type function is used to check the data type of the object

type(x)
Out[12]:
int

The Integer can be converted to float by method of Typecasting, which can be done as follows

In [51]:
b=float(x)
print(b)

1.0

Float

In [7]:
y=1.5
In [8]:
print(y)

1.5
In [13]:
type(y)
Out[13]:
float

The Float can be converted to integer by method of Typecasting, which can be done as follows

In [20]:
#We will be converting value in variable y to integer and assigning it to a 
a=int(y)
print(a)

1

Boolean

This store values as True or False

In [56]:
p=True
q=False
In [58]:
type(p)
Out[58]:
bool
In [59]:
type(q)
Out[59]:
bool

We can also typecast into Boolean from integer. Its interesting to note that 0 will transalte to False
and anything greater than 0 will be treated as True

In [68]:
x=1
y=2
z=0
w=-1
p=bool(x)
q=bool(y)
r=bool(z)
s=bool(w)
In [69]:
print(type(p))
print(p,q,r,s)

<class 'bool'>
True True False True
In [71]:
print(type(p))
print(type(r))
print(int(p))
print(int(r))

<class 'bool'>
<class 'bool'>
1
0

String

In [17]:
z='Python is easy'
In [18]:
print(z)

Python is easy
In [19]:
type(z)
Out[19]:
str

One important thing to note is that string is indexed, what I mean by that is that you can reference each element of string by using its index. In Python index starts from 0

In [25]:
#I am retrieving element at index 0 i.e. 1st element of string z
z[0]
Out[25]:
'P'

Now if we want to retrieve multiple objects we can do slicing. Which is done as follows:

string[start:end:step]
the argument and end is not included. So it will only fetch elements till end-1
step tells difference between consecutive elements that needs to be fetched. By default its 1

In [27]:
z[0:6:]
Out[27]:
'Python'
In [32]:
# In this case we will specify step as 2, such that it picks up every second element
z[0:6:2]
Out[32]:
'Pto'

We can also find out how many elements in the string

In [33]:
len(z)
Out[33]:
14

In strings there is also reverse indexing, that starts from -1

In [36]:
#Will print last element in string z
z[-1]
Out[36]:
'y'

Slicing can also be done using negative indexing. (If end is left blank it means till end of string)

In [38]:
z[-4::]
Out[38]:
'easy'

To Count the number of elements in a string , we can use function count

In [40]:
#Counts number of times s appears in string z
z.count('s')
Out[40]:
2

Changing the case of strings (uppercase/lowercase)

In [76]:
b='TRUST ME'
c='its easy'
In [77]:
print(b)
print(c)

TRUST ME
its easy
In [78]:
print(b.lower())
print(c.upper())

trust me
ITS EASY

Cancatenation of Strings

In [49]:
print(b+c)

TRUST MEits easy

Adding space in between

In [50]:
print(b+' '+c)

TRUST ME its easy

Another method of cancatenating strings is by using placeholders

In [79]:
print("{} when I say {}".format(b,c))

TRUST ME when I say its easy
In [80]:
print(b,c)

TRUST ME its easy
In [81]:
print(b,c,sep=',')

TRUST ME,its easy

Creating an application that will add two numbers

Lets use some of the concepts learned above to create a simple application.
We will use a function input that accepts input from user

In [82]:
x=input('Enter number one: ')
y=input('Enter number two: ')
z=x+y
print('The sum is {}'.format(z))

Enter number one: 10
Enter number two: 5
The sum is 105

The sum is wrong because, input function returns value as string. What Python simply did was cancatenate
x and y, because they were two strings seperated by +
We can fix this by typecasting input as int

In [83]:
x=input('Enter number one: ')
y=input('Enter number two: ')
z=int(x)+int(y)
print('The sum is {}'.format(z))

Enter number one: 10
Enter number two: 5
The sum is 15