Explain if-else statement in python

In this post, we will learn about if-else and nested if-else in python with an easy and simple example. So let’s start learning what is if-else and nested if-else in python.

what is if-else in python?

if-else is a keyword in python and it is used as a conditional block in which when the condition is true then if block is executed otherwise else block is executed.

Let’s take an example to understand the if-else block in python

number = int(input("ENter a number: "))
if number>5:
    print("number is greater then five")
else:
    print("number is not greater then five")

Output-1:

ENter a number: 6
number is greater then five

Output-2:

ENter a number: 4
number is not greater then five

Expaination

In the above example, the number is checked in the if block, and when a condition is true then code inside the if block is executed otherwise code inside the else block is executed.

that means if block is executed when your condition is true.

Important note while using if-else in python

1. else block is always written after if block (it is compulsory).
2. you can write only if block.
3. you can not write only else block (it will give an error because else block is always written after if block).
4. you can write more than one condition in if block using logical operators.

Let’s take an example to understand all the above notes of the if-else block.

only if statement

num = int(input("ENter a any number: "))
if num>7:
    print("number is greater then seven")

Output:

ENter a any number: 9
number is greater then seven

if a condition is not true then the above code does nothing (Because there is no else block).

only else statement gives error

num = input("ENter your name: ")
else:
    print("this is else block")

Output:

Desktop\allinpython\if-else.py", line 2
    else:
    ^
SyntaxError: invalid syntax

else block is always written after if block otherwise it will give SyntaxError.

if statement with multiple conditions

num = int(input("ENter a any number: "))
if num>4 and num<6:
    print("entered number is five")
else:
    print("entered number is not five")

Output-1:

ENter a any number: 6
entered number is not five

Output-2:

ENter a any number: 5
entered number is five

Now i hope so you understand all the basic concept of if-else in python, So it is time to start learning nested if-else in python.

what is nested if-else in python

A if-else statement placed inside another if or else statement is know as nesting of if-else.

let’s understand nested if-else with the help of example:

num1 = int(input("Enter any number: "))
if num1>10:
    if num1<15:
        print("number is less than 15")
    else:
        print("number is greater than 15")
        
else:
    if num1<5:
        print("number is less than 5")
    else:
        print("number is greater than 5")

Output-1:

Enter any number: 11
number is less than 15

Output-2:

Enter any number: 7
number is greater than 5

Hope this post add some value to your life – thankyou.

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if-elif-else in python