Quickly with Python - 05 - Exception Handling Video Lecture | Python- Mastering Development in Python - Software Development

thank you so much for joining me I'm
t-pain and welcome to another let's
learn Python so feel free to click on
the right side to use the skip ahead
feature to jump to a specific section or
the examples that you'd like to learn
we're going to be using Python 2.7 point
4 in this exercise you can download it
from python org slash get it this will
build heavily on the past lessons so
feel free to go back and watch those
again if anything is unclear so let's go
ahead and get started and open up idle
so let's say we had a script that
required user input but we only wanted
the user to input integer values what
would happen is if the user input
strings or words the code could break so
how do we handle that is with exception
handling and this is a way of handling
any kind of code that could possibly
break your script or files all right so
the the keywords that we're gonna learn
about are try and accept and try as
basically try to do something and except
it's like alright if something is
illegal do this instead and so let's try
an example of something that would break
our code so let's type an x equals 5
plus quotation marks ham in quotation
marks enter and now you'll see this
traceback
error call and say sty peri can't add
strings and intz together which makes
perfect sense so we're gonna try our new
exception handling and so type in try
colon enter and then type in x equals 5
plus ham again and type and enter delete
press backspace to jump back tab space
and type in except colon enter print
darn it because we knew it wouldn't work
enter enter and now it prints it without
any error being popped up or
interrupting our code so this is
extremely useful if you're writing
scripts and you want to catch anything
that could possibly
break your code and spit out any message
for the user or for debugging so another
key word that can be used with the try
and accept is the keyword pass and pass
is basically a way of not having
anything happen in here you don't have
to print space or print anything it's
just a way of saying hey just ignore
this so we're going to type in try :
x equals 5 plus ham again because 5 and
ham don't add up
backspace except colon pass enter enter
and now look at what happens it's just
using it to pass on to say hey just move
on past this whatever so passes a way of
saying hey ignore whatever came through
and just move on ok so another important
keyword to know about is the raise
keyword which can be used to force a
specific error or exception to be called
so we're going to type in a quick
example of it just typing raise space
type error and then open parentheses and
there's type hahaha close parenthesis in
quotes enter and what happens is were
spitting were returned an actual error
and it says trace back Bob la raise type
error and then here is the actual error
and the type error and the Texas
hahahahaha how he actually plants them
cool note that there are many other
exceptions or errors that can be raised
there's the zero division error the name
error the type error and many many more
so for more information please look up
Python documentation on pythons website
alright so the last exception keyword
we're going to go over is called finally
and finally always happens at the end of
the steps before the real errors are
returned so let's go ahead and punch in
try :
enter x equals 5 plus ham
enter backspace accept and then type in
zero division error and what this zero
division error is is we're declaring hey
if this specific type of error comes out
of the try area then this is how we're
gonna be handling it so this is a way of
declaring specifically what type of
error you're looking for otherwise if
you leave it blank
it'll just catch all the errors type in
enter print will not see this in quotes
and then we're going to backspace and
type in finally colon enter print space
the final word and quote enter enter and
so we see the final word is print
printed first and then the real air it
comes afterwards great
and so finally is used for doing any
last end stuff if you need it to
debugging stuff would go great right
here and finally and then the actual
error would be returned right here all
right yes thank you so much for watching
great job in keeping up today definitely
take a few minutes to investigate these
final examples as they really have
thought-provoking concepts within them
they go over a lot of the topics that we
went over also please do me a huge favor
and subscribe to my channel that way you
never miss another episode as I take
them out and thank you so much for your
support and keep the dream alive
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