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Learn Python by examples – Ex-16-20

Learn Python by examples – Ex-16-20

 
Note there are multiple ways to solve a problem.
Here is one solution.
 

Exercise 16: Write a program, say hello, using function
 

Solution:
 

Concept:

Simple function definition and calling function.
 

# function

def greet():
    print('Hello !')
    
greet()

Output:

Hello !


 
 

Exercise 17: Write a program add two numbers given by user, Ex: 30, 77 =>107
 
Concept:

Simple function, with two parameters
Handling input parameters and doing arithmetic operation.

 
Solution:
 

#passing arguments, and calling function

def add_numbers(a,b):
    c = a + b

    print('{} + {} = {}'.format(a,b,c))
    
x = int(input('Enter first number :>'))

y = int(input('Enter second number :>'))

add_numbers(x,y)


Output:

Enter first number :>22
Enter second nuber :>9
Enter third number :>100
9  is smallest

#option 2:

#using min() built-in function


a = int(input('Enter first number :>'))

b = int(input('Enter second number :>'))

c = int(input('Enter third number :>'))

print(min(a,b,c), ' is the smallest')


Output:

Enter first number :>30
Enter second number :>77
30 + 77 = 107


 
 
Exercise 18: Write a program to check, given number is odd or even
 
Solution:

 
Concept:
Defining small function which returns a value,
return value is used conditional if-else.
 


# return from function 


def is_even(num):
    if num % 2 == 0:
        return True
    else:
        return False

a = int(input('Enter a number :>'))

if is_even(a):
    print(' {} is even'.format(a))

else:
    print(' {} is odd'.format(a))

Output:

Enter a number :>4
 4 is even

Enter a number :>9
 9 is odd

 
 

Exercise 19: Write a simple calculator program for, addition, subtraction, multiplication, division.
 
Solution:

 
Concept:

Defining small functions, and calling functions in user interface,
Based on user input.
 


#arguments to func, return, and calling, in interface

def add_num(a,b):
    
    return a + b

def sub_num(a,b):
    
    return a - b

def mul_num(a,b):
    
    return a * b

def div_num(a,b):
    
        return a / b 


        

def my_calculator():
    
    x = int(input('Enter a first number :>'))
    
    y = int(input('Enter a second number :>'))
    
    choice = int(input('Enter your choice, 1-Addition,2-subtraction, 3-Multiplication, 4-Division :>'))
    
    result = None
    
    
    if choice == 1:
        
        result = add_num(x,y)
        
        print('{} + {} = {}'.format(x,y,result))
    
    elif choice == 2:
        
        result = sub_num(x,y)
        
        print('{} - {} = {}'.format(x,y,result))
        
    elif choice == 3:
        
        result = mul_num(x,y)
        
        print('{} * {} = {}'.format(x,y,result))
        
    elif choice == 4:
        
        if y != 0:
            
            result = div_num(x,y)
            print('{} / {} = {}'.format(x,y,result))
        else:
            print('Can't divide by zero')
        
    else:
        
        print('Invalid choice ')
        
    
my_calculator()


Output:

Enter a first number :>5
Enter a second number :>2
Enter your choice, 1-Addition,2-subtraction, 3-Multiplication, 4-Division :>4
5 / 2 = 2.5 

 
 

Exercise 20: Write a program print prime numbers up to 100

 
Solution:

 

Concept:
using for-loop, if-else in function.

 

# for, if , inside function

def is_prime(num):
    
    divisor = int(num/2)+1
 
    for i in range(2,divisor):
        if num % i == 0:
            return False

    return True
 
for num in range(2,100):
    if is_prime(num):
        print(num,end = ' ')
    


Output:

2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97