Conditional Statements
Indentation​
Indentation is a whitespace (space or tab) at the beginning of a line in a block of code to indicate scope of code
if Statement​
if statement allows for conditional execution of a statement based on the value of an expression.
Syntax:
if condition :
statements-1
statements-2
.....
.....
statements-n
Example:
a = 20
b = 10
if a==b :
print("A is equals to B")
Output:
A is Equals to B
In the above example, we are create a two variables a& b, in their stored values 20 & 10 respectively and check the if statement a==b if this condition is true the the output is A is equals to B.
if--else Statements​
if statement can have two outputs. the first output is if your comparison is true, the second if your comparison is false then output is only one.
Syntax:
if condition :
statements-1
statements-2
.....
.....
statements-n
else:
statements-1
statements-2
.....
.....
statements-n
Examples:
a = 20
b = 10
if a==b :
print("Equal")
else :
print("Not Equal")
Output:
Not Equal
In the above example, we are create a two variables a& b, in their stored values 20 & 10 respectively and check the if-else statement a==b if this condition is false so,the the output is Not Equal.
a = 10
b = 30
if a>b :
print("A is greater")
else :
print("A is Not smaller")
Output:
A is Not smaller
In the above example, we are create a two variables a& b, in their stored values 10 & 30 respectively and check the if-else statement a>b if this condition is false so,the the output is A is Not smaller.
age = int(input("Enter Your age :"))
if age >= 18 :
print("You are eligible for voting")
else:
print("You are not eligible for voting")
Output:
Enter Your age :15
You are not eligible for voting
num = int(input("Enter Number :"))
rem = num % 2
if rem == 0:
print("Given number is Even")
else:
print("Given number is Odd")
Output:
Enter Number :9
Given number is Odd
Example: Write a program which asks user to enter rate and quantity of a product. Your program should calculate and display the the bill amount as rate * quantity. If bill amount is more than 500 discount of 20% on bill and less than 500 then discount of 5% on bill.
rate, quantity = input("Enter rate and quantity :").split()
bill = int(rate) * int(quantity)
if bill > 500:
print("### 20% off ###")
print("Actual Bill",bill)
discount = (bill/100)*20
print("Discount",discount)
print("payble amount",bill-discount)
else:
print("### 5% off ###")
print("Actual Bill",bill)
discount = (bill/100)*5
print("Discount",discount)
print("payble amount",bill-discount)
Output:
Enter rate and quantity :20 50
"### 20% off ###"
Actual Bill 1000
Discount 200.0
payable amount 800.0
In the above program we create two variable rate and quantity and this variable we can give a input from user so we use input() function and this input function give message for user Enter rate and quantity : and in one input() we give multiple input so we use spilt() function.
In next line we create one variable bill and this variable we store calculation of int(rate) * int(quantity)
It first checks if the value of bill is greater than 500 using an if statement.
If the condition is true, then it prints ### 20% off ### to indicate that a 20% discount is being applied.
The program then prints the actual bill amount using the print function.
It calculates the discount amount by multiplying the bill amount with 20/100*(20%).
The program prints the discount amount and the payable amount after the discount by subtracting the discount amount from the actual bill amount.
If the value of bill is less than or equal to 500, the program prints ### 5% off ### to indicate that a 5% discount is being applied.
The program then follows the same steps as above to calculate and print the discount amount and the payable amount after the discount.
rate, quantity = input("Enter rate and quantity :").split()
bill = int(rate) * int(quantity)
disc_per = 0
if bill > 500:
disc_per = 20
else:
disc_per = 5
discount = (bill/100)*disc_per
print("### {}% ###".format(disc_per))
print("Actual Bill :",bill)
print("Discount :",discount)
print("Payble amount", bill-discount)
Output:
Enter rate and quantity :5 10
"### 5% ###"
Actual Bill : 50
Discount : 2.5
Payable amount 47.5
If else Ladder​
Python elif is used to execute a continuous chain of conditional logic ladder. In elif, there are multiple conditions and the corresponding statements as a ladder.
Syntax
if condition-1:
statements-1
statements-2
elif condition-2:
statements-1
statements-2
elif condition-3:
statements-1
statements-2
elif condition-4:
statements-1
statements-
else:
statements-1
statements-2
Code:
num = int(input("Enter number from 1 to 5 :"))
if num==1:
print("You selected option 1")
elif num==2:
print("You selected option 2")
elif num==3:
print("You selected option 3")
elif num==4:
print("You selected option 4")
elif num==5:
print("You selected option 5")
else :
print("You selected wrong input")
Output:
Enter number from 1 to 5 :5
You selected option 5
In the above example we create one num variable and in that variable we give input number from the user and checks whether the number is between 1 to 5. If the input is within the range, it displays the corresponding message, and if the input is out of range, it displays You selected wrong input.
Code:
name = input("Enter fruits or vegetable name :")
if name=="onion":
print("🧅")
elif name=="apple":
print("🍎")
elif name=="banana":
print("🍌")
elif name=="pineabpple":
print("🍍")
else:
print("Not avilable")
Output:
Enter fruits or vegetable name :orange
Not available
Example: Write a program to take input for marks of 5 subject and display the grade.
đź’ˇ HINT : Per=(total/500)*100
If the percentage greater than 90 “Grade: A” is printed.
If the percentage greater than 80 “Grade: B” is printed.
If the percentage greater than 70 “Grade: C” is printed.
If the percentage greater than 60 “Grade: D” is printed.
otherwise , Fail is Printed.
Code:
marathi,hindi,english,math,science = input("Enter marks of 5 subject :").split()
sum = int(marathi) + int(hindi) + int(english) + int(math) + int(science)
per = (sum/500)*100
print("Percentage :",per)
if per>=90:
print("Grade A")
elif per>=80:
print("Grade B")
elif per>=70:
print("Grade C")
elif per>=60:
print("Grade D")
else:
print("FAIL")
Output:
Enter marks of 5 subject :40 30 45 35 38
Percentage : 37.6
FAIL
In the above example, we takes input from the user in the form of marks obtained in five subjects Marathi, Hindi, English, Math, and Science. It then calculates the sum marks obtained and the percentage obtained by the student. Finally, based on the percentage obtained, it prints the grade of the student.
But This case If the condition sequence will change , then output will also change.👇👇 Because we have not set any boundary conditions.
marathi,hindi,english,math,science= input("Enter Marks of 5 Subject : ").split()
sum=int(marathi)+int(hindi)+int(english)+int(math)+int(science)
per=(sum/500)*100
print("Percentage :",per,"%")
if per>=60:
print("Grade D")
elif per>=70:
print("Grade C")
elif per>=80:
print("Grade B")
elif per>=90:
print("Grade A")
else:
print("FAIl")
So, Give Boundary conditions of the above Program. After give a boundary condition then sequence does not matter and our output also not change.
Code:
marathi,hindi,english,math,science= input("Enter Marks of 5 Subject : ").split()
sum=int(marathi)+int(hindi)+int(english)+int(math)+int(science)
per=(sum/500)*100
print("Percentage :",per,"%")
if per>=60 and per<70:
print("Grade D")
elif per>=70 and per<80:
print("Grade C")
elif per>=80 and per<90:
print("Grade B")
elif per>=90: and per<=100:
print("Grade A")
else:
print("FAIl")
Output:
Enter Marks of 5 Subject : 91 93 93 98 85
Percentage : 92.0 %
Grade A
Nested if​
A nested if is a flow control statement that’s the target of another if-statement. By nested-if statements, we mean to use an if-statement inside another if-statement.
Syntax:
if condition-1:
if condition-2:
if condition-n:
statement-1
statement-2
statement-n
Example:
jee = 110
hsc = 50
if hsc>60:
print("Congrats you clear HSC")
if jee>120:
print("Admmision Granted ")
else:
print("Sorry you did not cleared JEE")
else:
print("Sorry You need to imporoved your HSC Score")
Output
Sorry You need to imporoved your HSC Score
The code checks if a student has cleared their HSC with a score greater than 60. If they have, it checks if their JEE score is greater than 120. If it is, the program prints "Admission Granted". If the HSC score is less than or equal to 60, the program prints "Sorry You need to imporoved your HSC Score". If the JEE score is less than or equal to 120, the program prints "Sorry you did not cleared JEE".
Example:
Write a program to Find the Largest Number Among Three Numbers by using if,elif statement.
a = int(input("Enter a: "))
b = int(input("Enter b :"))
c = int(input("Enter c :"))
if a>b and a>c:
print("a is largest")
elif b>a and b>c:
print("b is largest")
else:
print("c is largest")
Output
Enter a: 300
Enter b :500
Enter c :100
b is largest
In the above example, we take input from the user in the form of numbers obtained in three numbers a, b & c. we are applying here the If else Ladder statement if a>b and a>c true so, print a is largest, b>a and b>c true so, b is largest otherwise print else statement c is largest.
Example:
Write a program to Find the Largest Number Among Three Numbers by using Nested-if statement.
a = int(input("Enter a: "))
b = int(input("Enter b :"))
c = int(input("Enter c :"))
if a>b:
if a>c:
print("a is largest")
else:
print("c is largest")
else:
if b>c:
print("b is largest")
else:
print("c is largest")
Output
Enter a: 10
Enter b :100
Enter c :100
c is largest
Now supply inputs say 10 as first number, then enter 20 as second number, and finally enter 30 as third number, we are apply here nested-if-else statement firstly, check if condition if a>b is true then enter in , thier is again if-else condition . if this condition will be true then print if statement otherwise else statement . if condition if a>b is false that time print else condition its have also if-else condition .