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welcome back aliens my name is 720 and
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let's continue with the series on Python
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in this video we will try to focus on
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files but why do we need files in the
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first place
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think about this let's say if you are
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working with a code and of course when
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you write a code you will use certain
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variables and in those variables you
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will be storing some data now most of
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the data which we use in variables are
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temporary data right if you want to
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count a variable if you want to store
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some data like temporary data you will
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store that in a variable but what if you
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want to save a data in a persistent way
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no I mean simply for a longer period now
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of course the moment you close the
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application you will lose all the data
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what I want is even if I close the
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application I want my data to be stored
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somewhere and that's where you need to
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find a permanent storage one of the way
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you can do that is by using a relational
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database example you can use MySQL you
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can use Oracle but then it also provides
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you a table structure right and those
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are complex stuff what if you want to
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store something for a longer period but
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then in a simple format and the best way
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to go for is text so let's imagine if we
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have a text file here which is my data
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and inside this my data I have some data
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you can see it's my name there there is
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code channel name and it's a programming
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channel and all those stuffs right so we
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have this data random data and I want to
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use this data in a code so how do I open
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this file in our code
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I know it seems difficult by the moment
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you say hey how can you open external
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file in our code back of your mind you
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might be thinking oh it will be very
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complex but don't worry as we mentioned
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before python is the easiest language
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and to do all this stuff we already have
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some inbuilt functions so let's do that
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so one of the function or method you can
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use here is known as open so you simply
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say open you have to pass two basic
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parameters here the first one is the
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file name itself and the file name here
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is my data okay so you have to make sure
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the file name do we have the extension
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for this I don't think so
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so have to mention the file name and you
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need to also mention the mode now it is
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mode here see when I work with a file of
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course there are different power
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you can use files one of these will be
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used file is to rate the file one reason
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to open a file is to write something in
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it or maybe to overwrite something in it
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so there are different purpose right to
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open a file in the same way here when
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you open a file you have to show your
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purpose do you want to read a file do
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you want to write a file now you want to
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thinking why does it even matter if I
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open a file I want to do whatever I want
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see the thing is when you work on a
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complex system you might be working with
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multiple threads you want to give
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certain permissions and to read a file
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we may achieve multi-threading but to
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write a file you have to make sure we
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are using only one thread or something
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like that
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again that's a complex stuff but time
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being imagine whenever you open a file
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it's very important for a system to know
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what your intentions are now how do you
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mention your intention it's very simple
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you just need to use odd here the moment
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you say our it means you are opening
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this file for greeting okay so we have
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done with the opening your file but then
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if you want to handle that file you will
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save that file somewhere so you will say
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F is equal to open so you can imagine
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this F is a file now it's not actually
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it's a simply object or Die reference
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but you can imagine okay so time when
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you can say this is a file now with this
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file you can do certain operations
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example I want to print file let's see
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what happens when you print F as it is
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so I'm printing F here let's see what
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what it says let's run this demo and you
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can see F is of type text I of the
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wrapper with name ma Gator with a mole
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are so it is giving you all different
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features so it is giving you everything
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except one thing which is the data of
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course how do you fetch data it's very
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simple actually so this open in fact
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when you talk about files it provides
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you certain methods to use what are the
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methods which we can use here is reading
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so we can use read to fetch the data
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let's see what happens now I'm using
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read and let's run this code oh we got
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everything so it's so simple to print a
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data from a file in Python now what if
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you don't want to print the entire file
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you want to print only one line the
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first line do we have an option so the
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moment you say control space you can see
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so it has certain names we have read we
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have read line and then we have read
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lines
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okay so let's use read line here now
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when they said read line and let's see
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what happens
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read line okay just next to mine so you
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can see when you say read it will print
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everything when you said we'd line and
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that's one this code you can see it only
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prints the first line
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oh okay so that means when you use red
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line it will print on the first line
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what if I want to print the second line
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so it's very simple just copy this code
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so every time you said read it has a
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inbuilt pointer inside it so when you
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say read line the pointer will move to
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the second line now and then when you
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say to read right now it will fetch the
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second line it will the pointer will
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move to the third line let's verify so
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let's run this code you can see we are
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getting my name is know already and
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second line is the disco on YouTube now
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you are you thinking why we got this
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space here it's because print itself
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will give you a new line and in this
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data as well you have new line right so
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after every line you have a new line
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plus print will also give you a new line
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we don't want a new line after print so
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we'll say and so let's put a symbol by
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mentioning hash let's say when you
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search it means we have done with the
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line 1 and line 2 okay so you can see
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this is what it does it says hash okay
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so we should be doing that before as
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well by its time let's move that so yes
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so the idea is when you say when he does
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put and it will by default just newline
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so now we know how to work with red line
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and read can we mention the line number
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okay that's a question let's see if I
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mentioned line number four and if I
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don't use second one let's see what
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happens we accept it
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oh it is only printing for characters
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okay so when you say four it will print
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only four characters that's great so you
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can use this function and is how it
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works but how do we write data so we
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know how to read now I want to know how
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to write the data so in order to write
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the data first of all let me remove that
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C we cannot use our to write something
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we have to use W to write some things
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what I do is let me use another file
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here we'll say f1 and let me open that
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file and you have to mention the file
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name here as well so I will say the file
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name here is ABC and we have to mention
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the right commands the moment you say w
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it means you are trying to write
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something in a file but hold on if you
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see on the left hand side we don't have
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any file as ABC now what will happen so
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now it is smart here so when you say
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open a file with a write more it will
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first check do we have a file there so
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we don't have a file right so it will
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create a file for you let me show you so
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if I run this code
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you can see we are getting a new file
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which is ABC and if I open this file yes
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it's a text format you can see we don't
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have any data of course we don't have a
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data there right so let's ring something
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and the way you can print data is by
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saying f1 dot and you can use a write
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command so you can say it right and here
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you can write something I will say
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something ok let's see what happens now
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so let's run this code and you can see
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we are not printing anything in the
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console that's why we're not getting any
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stuff here let's go back to ABC and you
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can see a DC we got something so you can
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write multiple data here you can also
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write something let's say f1 dot and you
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will say people let's run this code and
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you can see in ABC we to get something
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and people of course you can give a
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space in between while writing this code
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ok so this makes sense right
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ok so what if if I say f1 dot right so I
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know that in my file we already have
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something and people I want to say
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something people laptop so in my file I
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want to also add a laptop how do I do
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that so here you will simply say laptop
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right that's what we are expecting here
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but the twist is if I have this code
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look at the output look at the file can
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you see that we lost all the previous
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data right so we lost something we lost
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people we only have laptop now it's
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because when you say W it simply means
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write define what if we don't want to
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write a file you want to append
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something if I said let's say here if I
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say mobile I want to obtain the moment
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after laptop in that case you will open
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a file with a so a means a painter so W
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is right artists raid a is a painter and
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now let's run this code and if I go back
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to ABC you can see we have laptop and
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mobile so remember this thing we have
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our we have W and we have a ok now what
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I wanna do is we have two files right we
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have ABC and we have my data what our do
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is I want to copy everything from my
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data I want to save that in ABC that's a
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difficult step right so first read all
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the data from my data and then write
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everything in ABC two steps first of all
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let's understand how do you fetch
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everything from my data we have seen one
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way right we can use red line but then
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how many times you will say we'd line
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how do we know when your file will get
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over that will be impossible to track so
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the best way is you can actually use
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Ford lobe and you say for data in F
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right so what it will do is it will run
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a loop and on a file F of course it will
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run a loop and will try to fetch
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everything one by one so if you can see
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if I print if I print data one by one
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and look at the output it will print
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everything we have extra line then right
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so but timed ignore that it the
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important thing is it is fetching
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everything one by one so if you have to
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use the same quads say when you write in
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ABC as well so of course you will use a
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for loop here you will say for the data
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in F and then every time you run this
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loop you have to say F 1 dot right and
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you will write a data which is data
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right so now it will in ABC you will
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have all that about from my data let's
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run this code go back to ABC and can you
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see that we got all this data here
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awesome right so this is how you can
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work with files so we can use read we
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can use right we can use append now just
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to show you something I have one more
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thing so let me just remove this stuff
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from here so we have a file which is my
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data right now if you can see on left
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hand side we have big as well so there's
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a jpg image if I open that you can see
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it's my photo here so this is of a
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simple photo what our doors I want to
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copy this file or maybe I want to print
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all the data about that file can you
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print data of course right when you talk
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about image it is made up of the binary
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formats wide the pixel intensity all
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those values of course those are numbers
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itself let me try to print the date of
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image let's see how that looks
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so I'll say for I in F I don't know if
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will it work or not let's try let me
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print I so let's see how exactly it
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looks like let's run this code oh we got
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an error
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it says char map okay so cannot decode
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oh that's the issue
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the thing is in files we have two
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different modes one is character mode
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and second is binary mode now when you
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work with file and that file has data
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like actors numbers you can use a
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character format but here you're walking
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with a file wide which is an image and
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when you work with image we don't have
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characters inside image right we have
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numbers we are binary format and that's
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why you need to read this file in a
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binary format now how do you mention
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that it's very easy simply use our B so
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RB means read binary and now let's run
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this code okay see that this is my
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values of the image okay so all these
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are exact code and that's why it is
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printing like there's no hexa values
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yeah so you can see we are putting all
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these values but then it does
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any sense all right this thing doesn't
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make any sense what I will do is I will
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save this data in a particular file
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maybe another image how do I copy this
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image and make another image it's very
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simple let's create a file oh it's a
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file one equal to open and the way we
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have done before but then this time I
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will give a different name I will say my
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hey not my Tita this time my pick dot
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jpg and then we will give a mold so any
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guess of course we have to say right but
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then right binary you have to make sure
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that we like we use right BAM binary
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instead of printing it you will say f1
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dot right and you will write whatever is
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coming from the file one which is upon
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this file let's run this code there is
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no error go back to okay so you contain
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yourself you got my Pig
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open that oh we got a picture okay so
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you can see we have two copies of my
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image this is what amazed the second
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image right so this is how you can work
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with files with characters and Manolis
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let me know in the comment section if
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you are enjoying this series and if you
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have any doubts as well so that's it hit
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that like button and do subscribe for
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for the video bye bye
