if statement in Python programming language

In this tutorial, we will learn about if statement in Python programming language

In the Python programming language, the if..elif..else statement is used for decision making.

If statement in Python

Declaration

Syntax

Flow diagram of if statement in Python

Here, Initially, the program test expression is evaluated by if condition.

When the text expression is true, the body of if statements are executed. When the test expression is false, the flow of control skips the body of if statements and comes out of if body.

Example

//#Example for if statements in Python
age=20; #integer value
if age>18:
    print("you are a teen age boy")
    //#body of if part
   // #if test expression is true, body of if executed
    //#if test expression is false, skip execution from if

In the above program, initially, age is initialized by 20.

age >18 is the test expression

When the test expression is evaluated, it returned true, then statements inside the body of if is executed.

When we execute the above program, it will produce the following result

You are a teenage boy

If – else statement in Python

Declaration

Syntax

Initially, the program’s test expression is evaluated by if condition. When the text expression is true, the body of if statements are executed. When the text expression is false, the flow of control skips body of if statements and comes to else part for execution.

Flow diagram of if else statement in python

Program 1

//#this program use to check voting availability based on age
//#using if condition in Python
age=32; //#integer variable
if age>=18: //#if the condition is true, this statement is executed
    print("You are allowed to voting")
else:       //#if the condition is false, this statement is executed
    print("You are allowed to voting");

When we execute the above program, it will produce the following result

you are allowed to voting

If – elif – else statement in Python

Declaration

Syntax

When the test expression 1 is true, the body of if statement(s) are executed.

When the test expression 1 is false, the flow of control enters the elif part to evaluate test expression 2

when the elif part is true, test expression 2 is executed.

When the test expression 2 is false, test expression moves on to test expression 3

When the test expression 3 is true, the flow of control executes the body of the elif 2 statement(s)

When the test expression 3 is false, the flow of control executes else part statements and exit from the loop.

Flow diagram of if elif – else statement

Program 1

//#Checking number is negative , positive or zero
num=0 //#int variable
if num>0: //#if the condition is true, this statement is executed, if not
    print(num," is te positive number");
elif num<0://#if the condition is true, this statement is executed
    print(num," is te negative number");
else://#otherwise finally this statement is executed
    print("Other one is zero only");

In the above program, variable num is initialized zero(0)

num>0, num<0 are test expressions .

When the var num is positive, positive statements is displayed with the number(if part)

if var num is negative, the negative statement is displayed with the number(elif part)

both statements are false else part statements printed

When we execute the above program, it will produce the following result

Other one is Zero only

Program 2

//#Check natural number 1 -9
x=6  //#integer variable
if x==1:
   print("One")
elif x==2:
   print("Two")
elif x==3:
   print("Three")
elif x==4:
   print("Four")
elif x==5:
   print("Five")
elif x==6:
   print("Six")
elif x==7:
   print("Seven")
elif x==8:
   print("Seven")
elif x==9:
   print("Seven")
else:
    print("Zero")

When we execute the above program, it will produce the following result

Zero

Program 3

The model electricity bill is calculated as follows

Electricity bill calculator using if elif else statements in Python

#calculate electicity bill for usage
'''1 - 50 -5/=
51 - 100 - 7/=
101 - 200- 10/=
201 - 300 - 15/=
above 300 - 20/='''

unit = 500 #usage unit
if(unit >0)& (unit <=50):
  print("Your bill is",unit*5)
elif(unit >=51)& (unit<=100):
  print("Your bill is",50*5+(unit-50)*7)

elif(unit >=101)& (unit<=200):
  print("Your bill is",50*5+(100-50)*7+(unit-100)*10)

elif(unit >=201)& (unit<=300):
  print("Your bill is",50*5+(100-50)*7+(200-100)*10+(unit-200)*15)

elif(unit >=300):
  print("Your bill is",50*5+(100-50)*7+(200-100)*10+(300-200)*15+(unit-300)*20)

When we execute the above program, it will produce the following result

(‘Your bill is’, 7100)

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