Python if-else

Python if-else

The else statement is associated with if statement. An else statement executes if the conditional expression in if the statement becomes false or a Zero value.

If the conditional expression is false, then control transfers to the else block. An else statement is optional, and there could be only one else statement.

Syntax

The syntax of the if…else statement is following.

if expression:  
    Statement
 else:
    statement

The colon (:) is important because it splits the condition from the statements to be executed after the evaluation of the condition. This is especially important for statements where there is only a single statement and the bracket ( ) is not used.

Flow Diagram

In the above flowchart, first it checks the condition if the condition is true, then conditional code (if statement) will be executed. If the condition is false, then else block (else statement) will be executed.

The if…else statement examples are the following:

1. Write a program to check number is even or odd

num = int(input("Enter the number"))
 if num%2==0 :
     print(num,"is a even number")
 else:
     print(num,"is a odd number ")

Output:

Enter the number 25
25 is odd number

1. Write a program to check the voter’s age for valid for voting or not

age = int(input("Enter the age"))
 if age<18:
     print("You are not eligible for Voting")
 else:
     print("You are eligible for Voting")

Output:

Enter the age 17
You are not eligible for Voting

1. Write a program to display student marks 

score_theory = int(input("Enter theory marks:"))
 practical = int(input("Enter practical marks:"))
 total = score_theory+practical
 if practical+score_theory>100:
     print("Please check the input. Score exceeds total possible score.")
 else:
     print("Score validated. Your total is: ",total)

Output:

 Enter theory marks: 60
 Enter practical marks: 45
 Score validate. Your total is: 95