Strings in Python

What is String in python?

• In Python, String is a sequence of characters enclosed by either single quotes or double-quotes.

• Example: 'Python', "Geek4Tutorial"

• Strings are immutable.

• Each value in a string is called character. 

Creating a String:

• Strings can be created by enclosing the sequence of characters inside a single quote or double quote and assigning it to a variable.

• Sometimes triple quotes can also be used to create a string, even though triple quotes are used to represent Multiline strings and Docstrings.

• We can access the characters(element) in the string just like the index using index position.

Example python programs: Functions basics

Simple python programs to practice:

1) Write a Python function Factorial(n) which returns the factorial of the given number(n).

2) Write a Python function, Square(num) which returns the square of the given number(num).

3) Write a Python function, Sum(n) which returns the sum of first n numbers.

4) Write a Python function, Palindrome(num) that accepts an integer num as input and returns true/false based on condition.

    Ex: num = 12321 ---> output = 12321 ----> then given number is palindrome.

5) Write a Python function, check_strong_number(num) that accepts a positive as input, and returns true/false based on condition.

• A number is said to be a Strong number if the sum of the factorial of each digit is equal to the given number.

   Ex: 145 is strong number as (1! =1) + (4! = 24) + (5! = 120) = 145.

Lists in Python

What is a List?

• The list is one of the most common collection datatypes in Python which is ordered and mutable (changeable).

• It is used to store a group of an element together in a sequence.

• A list can store both homogenous and heterogeneous elements i.e., a single list may contain data types like integers, floats, strings as well as objects.

• Individual value in a list is called an element.

• These elements will be stored in a contiguous memory location.

• For Ex:
• Number1 = 10, 
• Number2 = 20, 
• Number3 = 30, 
• Number4 = 40 

• These individual variables can be represented in a list as

• Number_list = [ 10, 20, 30, 40 ]

Functions in Python basics

Functions In python:

• Set of instructions to perform a specific task.
• Below is the syntax of functions in python:

                   def function_name([arg1,....,arg n]):

                          statement 1

                          ........

                          statement n

                          [return value]

                   variable = function_name([value1,......,value n])

Control Structures

• In general, Control structures decide the flow of the program execution.

• The most commonly used control structures in python are

• Sequential: control flows through all the statements, in the order of how the code is written.

• Selection: Depends on the condition, control flows to the different statements.

• Iteration: Certain blocks of code(statements) will be executed repeatedly.