Notes

### **Python Function**

def hello():
print('Hello World!')

# call the function
hello()

print('Outside function')

# function with two arguments
def add_numbers(num1, num2):
sum = num1 + num2
print("Sum: ",sum)

# function call with two values
add_numbers(15, 41)


# function definition
def find_square(num):
result = num * num
return result

# function call
square = find_square(3)

print('Square:',square)

import math

# sqrt computes the square root
square_root = math.sqrt(4)

print("Square Root of 4 is",square_root)

# pow() comptes the power
power = pow(2, 3)

print("2 to the power 3 is",power)

### **Benefits of Using Functions**

# function definition
def get_square(num):
return num * num

for i in [1,2,3]:
# function call
result = get_square(i)
print('Square of',i, '=',result)

### **Function Argument with Default Values**

def add_numbers( a = 7, b = 8):
sum = a + b
print('Sum:', sum)


# function call with two arguments
add_numbers(2, 3)

# function call with one argument
add_numbers(a = 2)

# function call with no arguments
add_numbers()

# Python Keyword Argument

def display_info(first_name, last_name):
print('First Name:', first_name)
print('Last Name:', last_name)

display_info(last_name = 'Iqbal', first_name = 'Tamim')

# Python Function With Arbitrary Arguments

# program to find sum of multiple numbers
def find_sum(*numbers):
result = 0

for num in numbers:
result = result + num

print("Sum = ", result)

# function call with 3 arguments
find_sum(1, 2, 3)

# function call with 2 arguments
find_sum(4, 9)

### **Python Recursive Functiont**

def factorial(x):

if x == 1:
return 1
else:
return (x * factorial(x-1))


num = 5
print("The factorial of", num, "is", factorial(num))

### **Python Lambda/Anonymous Function**



```
# We use the lambda keyword instead of def to create a lambda function.
lambda argument(s) : expression
Here,
argument(s) - any value passed to the lambda function
expression - expression is executed and returned
```



# declare a lambda function
greet = lambda : print('Hello World')

# call lambda function
greet()

# lambda that accepts one argument
greet_user = lambda fname, lname : print('First Name:', fname, ' Last Name: ', lname)

# lambda call
greet_user('Atique', 'Rahman')

### **Global, Local and Nonlocal**

# Python Local Variables

def greet():

# local variable
message = 'Hello'

print('Local', message)

greet()

# try to access message variable
# outside greet() function
print(message)

# declare global variable
message = 'Hello'

def greet():
# declare local variable
print('Local', message)

greet()
print('Global', message)

# outside function
def outer():
message = 'local'

# nested function
def inner():

# declare nonlocal variable
nonlocal message

message = 'nonlocal'
print("inner:", message)

inner()
print("outer:", message)

outer()

def outer_function():
num = 20

def inner_function():
global num
num = 25

print("Before calling inner_function(): ", num)
inner_function()
print("After calling inner_function(): ", num)

outer_function()
print("Outside both function: ", num)