Python | Set 3 (Strings, Lists, Tuples, Iterations)

In the previous article, we read about the basics of Python. Now, we continue with some more python concepts.

Strings in Python:

A string is a sequence of characters that can be a combination of letters, numbers, and special characters. It can be declared in python by using single quotes, double quotes, or even triple quotes. These quotes are not a part of a string, they define only starting and ending of the string.  Strings are immutable, i.e., they cannot be changed. Each element of the string can be accessed using indexing or slicing operations.

Python

# Assigning string to a variable
a = 'This is a string'
print (a)
b = "This is a string"
print (b)
c= '''This is a string'''
print (c)

Output:

This is a string
This is a string
This is a string

Lists in Python:

Lists are one of the most powerful data structures in python. Lists are sequenced data types.  In Python, an empty list is created using list() function. They are just like the arrays declared in other languages. But the most powerful thing is that list need not be always homogeneous. A single list can contain strings, integers, as well as other objects. Lists can also be used for implementing stacks and queues. Lists are mutable, i.e., they can be altered once declared. The elements of list can be accessed using indexing and slicing operations.

Python

# Declaring a list
L = [1, "a" , "string" , 1+2]
print L
#Adding an element in the list
L.append(6)
print L
#Deleting last element from a list
L.pop()
print (L)
#Displaying Second element of the list
print (L[1])

The output is:  

[1, 'a', 'string', 3]
[1, 'a', 'string', 3, 6]
[1, 'a', 'string', 3]
a

Tuples in Python: A tuple is a sequence of immutable Python objects. Tuples are just like lists with the exception that tuples cannot be changed once declared. Tuples are usually faster than lists.

Python

tup = (1, "a", "string", 1+2)
print(tup)
print(tup[1])

The output is : 

(1, 'a', 'string', 3)
a

Iterations in Python: Iterations or looping can be performed in python by ‘for’ and ‘while’ loops. Apart from iterating upon a particular condition, we can also iterate on strings, lists, and tuples.

Example 1: Iteration by while loop for a condition

Python

i = 1
while (i < 10):
    print(i)
    i += 1

The output is: 

1
2
3
4
5
6
7
8
9 

Example 2: Iteration by for loop on the string

Python

s = "Hello World"
for i in s:
    print(i)

The output is: 

H
e
l
l
o
 
W
o
r
l
d

Example 3: Iteration by for loop on list

Python

L = [1, 4, 5, 7, 8, 9]
for i in L:
    print(i)

The output is: 

1
4
5
7
8
9

Example 4: Iteration by for loop for range

Python

for i in range(0, 10):
    print(i)

The output is: 

0
1
2
3
4
5
6
7
8
9 

• Next Article – Python: Dictionary and Keywords
• Quiz on Data Types in Python