Python-3.4.3/C4/Getting-Started-with-Functions/English-timed

Time	Narration
00:01	Welcome to the spoken tutorial on Getting started with functions.
00:06	In this tutorial, we will learn to, Define a function Define functions with arguments and use docstrings.
00:17	To record this tutorial, I am using Ubuntu Linux 16.04 operating system Python 3.4.3 and IPython 5.1.0
00:32	To practise this tutorial, you should know how to use tuples. If not, see the relevant Python tutorials on this website.
00:44	First we will learn about functions.
00:48	A function is a portion of code within a larger program that performs a specific task.
00:55	Functions are useful in reusing the code and eliminate code redundancy.
01:01	Functions are also used to organise our code into manageable blocks.
01:07	Here is the syntax for defining the functions.
01:11	def is the keyword which defines the function name.
01:15	colon is used to mark the end of the function name.
01:19	docstring is the documentation string to describe what the function does. It is an optional, but recommended.
01:29	Statement makes the function body and it must have 4 indentation level.
01:36	return statement is to return a value from the function and it is also indented by 4 spaces.
01:44	Now we will understand the functions with an example.
01:49	Consider a mathematical function f of x is equal to x squared.
01:55	Here x is a variable. f of x changes when x changes.
02:02	Let us define our function f of x.
02:06	The first line def f of x is used to define the function name and its parameters.
02:13	The second line uses the function parameters to return the required value.
02:19	Let us start ipython. Open the terminal.
02:24	Type ipython3 and press Enter.
02:29	From here onwards, remember to press the Enter key after typing every command on the terminal.
02:36	Type, def f inside brackets x colon return x asterisk x and press the Enter key two times.
02:47	Let us call the f of x with different arguments.
02:51	Type, f inside brackets 2 f inside brackets 2.5 It returned 4 and 6.25 respectively.
03:05	Now let us see how to write functions without arguments.
03:10	Type the code as shown. It defines a new function named greet which will print "No function arguments"
03:21	Now we will call the function as,greet open and close parentheses
03:28	Note that it is not mandatory for a function to return values.
03:33	The function greet neither takes any arguments nor returns any value.
03:40	Next we will learn how to comment in a code.
03:44	Documenting/commenting code is a good practice.
03:48	Docstrings are triple quoted comments entered just after the function definition. It implies what the function does.
03:57	Let us write a function which returns average of two numbers.
04:02	Type the code as shown. and press the Enter key two times. Comments within triple quotes give a clear explanation about the code.
04:14	Type, avg question mark Here we can see the docstring of the function avg.
04:23	Now let us pass 3 and 5 as values to the arguments a and b to the function avg.
04:31	Type, avg inside brackets 3 comma 5 We get 4.0 as output.
04:41	Pause the video.Try this exercise and then resume the video.
04:47	Write a function circle which returns the area and perimeter of a circle with given radius r.
04:54	Switch back to the terminal for the solution.
04:58	Type the code as shown. Press the Enter key two times.
05:05	The circle function requires us to return two values.
05:10	A python function can return any number of values in the form of a tuple.
05:16	Let us call the function circle as, a comma p is equal to circle inside brackets 6
05:25	Now Type, print inside brackets a comma p
05:31	We can see the output as area and perimeter of a circle of radius 6.
05:38	This brings us to the end of this tutorial. Let us summarize.
05:44	In this tutorial, we have learnt to, Define functions in Python Call a function by specifying the function name
05:54	Write docstrings to a function by putting it as a triple quoted string Pass parameters to a function Return values from a function.
06:06	Here are some self assessment questions for you to solve 1. How many arguments can be passed to a Python function?
06:15	2.Write a function to find the area of a rectangle.
06:20	And the answers, 1. Any number of arguments can be passed to a Python function.
06:28	2. We can write a function to find the area of a rectangle as:def rectangle underscore area inside brackets l comma b colon return l asterisk b
06:42	Please post your timed queries in this forum.
06:46	Please post your general queries on Python in this forum.
06:51	FOSSEE team coordinates the TBC project.
06:55	Spoken Tutorial Project is funded by NMEICT, MHRD, Govt. of India. For more details, visit this website.
07:04	This is Priya from IIT Bombay signing off. Thanks for watching.

Contributors and Content Editors

Pratik kamble