Functions.py

# Declaring and Calling a Function
# syntax
# Declaring a function
def function_name():
    codes
    codes
# Calling a function
function_name()


# Function without Parameters
def generate_full_name ():
    first_name = 'Harshal'
    last_name = 'Raikwar'
    space = ' '
    full_name = first_name + space + last_name
    print(full_name)
generate_full_name () # calling a function

def add_two_numbers ():
    num_one = 2
    num_two = 3
    total = num_one + num_two
    print(total)
add_two_numbers()


# Function Returning a Value
def generate_full_name ():
    first_name = 'Harshal'
    last_name = 'Raikwar'
    space = ' '
    full_name = first_name + space + last_name
    return full_name
print(generate_full_name())

def add_two_numbers ():
    num_one = 2
    num_two = 3
    total = num_one + num_two
    return total
print(add_two_numbers())


# Function with Parameters
def greetings (name):
    message = name + ', welcome to Python for Everyone!'
    return message

print(greetings('Harshal'))

def add_ten(num):
    ten = 10
    return num + ten
print(add_ten(90))

def square_number(x):
    return x * x
print(square_number(2))

def area_of_circle (r):
    PI = 3.14
    area = PI * r ** 2
    return area
print(area_of_circle(10))

def sum_of_numbers(n):
    total = 0
    for i in range(n+1):
        total+=i
    print(total)
sum_of_numbers(10) # 55
sum_of_numbers(100) # 5050


# Passing Arguments with Key and Value
def print_fullname(firstname, lastname):
    space = ' '
    full_name = firstname  + space + lastname
    print(full_name)
print_fullname(firstname='Harshal', lastname='Raikwar')

def add_two_numbers (num1, num2):
    total = num1 + num2
    print(total)
add_two_numbers(num2=3, num1=2) # Order does not matter


# Function Returning a string
def print_name(firstname):
    return firstname
print_name('Harshal') # Harshal

def print_full_name(firstname, lastname):
    space = ' '
    full_name = firstname  + space + lastname
    return full_name
print_full_name(firstname='Harshal', lastname='Raikwar')


# Function Returning a number
def add_two_numbers (num1, num2):
    total = num1 + num2
    return total
print(add_two_numbers(2, 3))

def calculate_age (current_year, birth_year):
    age = current_year - birth_year
    return age;
print('Age: ', calculate_age(2021, 1821))


# Function Returning a boolean
def is_even (n):
    if n % 2 == 0:
        print('even')
        return True    # return stops further execution of the function, similar to break 
    return False
print(is_even(10)) # True
print(is_even(7)) # False


# Function Returning a list
def find_even_numbers(n):
    evens = []
    for i in range(n+1):
        if i % 2 == 0:
            evens.append(i)
    return evens
print(find_even_numbers(10))


# Function with Default Parameters
def greetings (name = 'Harshal'):
    message = name + ', welcome to Python for Everyone!'
    return message
print(greetings())
print(greetings('Harshal'))

def generate_full_name (first_name = 'Harshal', last_name = 'Raikwar'):
    space = ' '
    full_name = first_name + space + last_name
    return full_name

print(generate_full_name())
print(generate_full_name('John','Wick'))

def calculate_age (birth_year,current_year = 2019):
    age = current_year - birth_year
    return age;
print('Age: ', calculate_age(1819))

def weight_of_object (mass, gravity = 9.81):
    weight = str(mass * gravity)+ ' N' # the value has to be changed to string first
    return weight
print('Weight of an object in Newtons: ', weight_of_object(100)) # 9.81 - average gravity on Earth's surface
print('Weight of an object in Newtons: ', weight_of_object(100, 1.62)) # gravity on the surface of the Moon


# Arbitrary Number of Arguments
def sum_all_nums(*nums):
    total = 0
    for num in nums:
        total += num     # same as total = total + num 
    return total
print(sum_all_nums(2, 3, 5))


# Default and Arbitrary Number of Parameters in Functions
def generate_groups (team,*args):
    print(team)
    for i in args:
        print(i)
generate_groups('Team-1','Harshal','Elon','Jeff','Bill')


# Function as a Parameter of Another Function
#You can pass functions around as parameters
def square_number (n):
    return n * n
def do_something(f, x):
    return f(x)
print(do_something(square_number, 3))