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

• Difficulty Level : Easy
• Last Updated : 28 Jun, 2021

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. It can be declared in python by using double-quotes. Strings are immutable, i.e., they cannot be changed.

• Python

# Assigning string to a variable

a = "This is a string"

print (a)

Lists in Python 
Lists are one of the most powerful tools in python. 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 objects. Lists can also be used for implementing stacks and queues. Lists are mutable, i.e., they can be altered once declared.

• Python

# Declaring a list

L = [1, "a" , "string" , 1+2]

print L

L.append(6)

print L

L.pop()

print L

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 : 

123456789 

Example 2: Iteration by for loop on string

• Python

s = "Hello World"

for i in s :

    print (i)

The output is : 

HelloWorld

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 : 

145789

Example 4 : Iteration by for loop for range

• Python

for i in range(0, 10):

    print (i)

The output is : 

0123456789