Functions and Doc Strings Tutorial

# Function helps in code reuseability

##########################################

## Example of built in function

# a = 9
# b = 8
# Sum is a inbuilt function in Python
# takes tuple or list (more, general Iterables) as input
# c = sum((a, b))
# print(c)  # Output : 17


##########################################

## Example of user defined function

## The keyword def introduces a function definition.
# It must be followed by the function name and
# the parenthesized list of formal parameters.
# The statements that form the body of the function
# start at the next line, and must be indented.

# def function1():
#     print("Hello you are in function 1")


# function1()  # Output : Hello you are in function 1

##### Functions with Parameter & Return Statement ####

# The 'return' statement returns with a value from a function.
# 'return' without an expression argument returns None
# if no 'return' statement used in function ,
# then function returns None

# print(function1())


# Output : Hello you are in function 1 (due to function call)
#        : None (due to no return statement)

## Functions with parameters

# def function2(a, b):
#     print("You are in function 2,", "Sum :", a + b)


# function2(5, 7)


# Output :You are in function 2, Sum : 12


# def function3(a, b):
#     average = (a + b) / 2
#     print("Average :", average)


# function3(5, 7)


# Output : Average : 6.0


# If we want to store value calculated by function in a variable
# We have to use return statement
# def function4(a, b):
#     average = (a + b) / 2
# print("Average :",average)
# return average


# val = function4(5, 7)
# print(val)


# Output : 6.0


################ Doc strings ##################

# Used to store information about function
# """ Documentation """ or ''' Documentation '''
# # This is not a comment but docstring ...
# ...if written as first line in function
# written elsewhere in function treated as comment
# def function5(a, b):
#     '''This is a function which calculates average of two numbers'''
#     average = (a + b) / 2
#     return average


# print(function5.__doc__)
# Output : This is a function which calculates average of two numbers

# docstring is helpful to know about functions
# in diiferent imported modules
# Also if we have large no. of functions
# we can use docstring to know about function