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Let's suppose a scenario where we have multiple Sears files and each of these files have an extra coma,

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which is unwanted, and we want to remove that coma of the ends of each file.

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And of course, we want to use Python to do that.

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So we want to automate the process instead of going through each file and deleting that it could be

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a thousand 2000 files.

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You don't want to do that.

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It's very easy to do with Python.

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So in this video, we're going to remove a comma, the lost character from a C as we file.

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But let's slow down a bit and let's work on one single file first.

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So I'm going to remove two of these files and just work on one of them in the next video.

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Then we will work on multiple files to remove the lost character of all the files.

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So see, as we files are just another type of text file, they happen to have a C USB extension, but

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you can open them in a text editor.

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So these are files that are separated by commas by separating these files by a comma.

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You have this well-defined structure to represent data.

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So, for example, we have this idea and so we have rows.

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34 is the idea for the first item?

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Fifty six is the idea for the next slide.

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Some five is the idea for the other item and so on.

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But then we want to remove this comma.

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Let's see how to do that in Python with open.

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Of course, we want to use the open methods file three that see us V..

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And what do we want to do?

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We want to get the contents of the file first.

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So we want to open the file in read mode.

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As foil and grab the contents with file that reads so we save the contents and the contents variable.

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Now see if we got that right.

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So on intent and print content.

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And yet, so that is the content.

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So this is a string, a plane, python string and as you know, with strings, we can do slice operations,

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for example, we can get all the characters, but the last one wrong, that's.

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And you see that the coma is not there anymore because a string has an indexing system embedded, so

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the less character has an index of minus one.

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That means the coma has an index of minus one.

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And when you do this, you're saying, give me all the items from the item with index zero, which is

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I.

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So that as an index of zero, this as an index of one to three, four, eight and so on.

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And you also have this a negative indexing so minus one minus two, minus three and so on.

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So we get a zero, we get one two three and minus one.

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So minus one is not included.

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You can run this again.

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You get the same thing.

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So that is the equivalent of that.

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So this is considered to be better because you avoid having to ride the zero there.

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Of course, if you right minus two there and run.

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The lost zero is going to go way.

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Also minus three.

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Like that and so on, so minus one is what we need, and we want to stall this results in a new variable.

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So let's say modified contents eagles to vet content with that slice.

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Some modified content now has no comma of the ends.

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What do we want to do with the modified content?

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Stream now is open a new file.

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Now here you have to take a decision.

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You either ride the same file name or file that see as V as here.

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And that means you will override this file with the new content, which does not have a comma, or you

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can create a new file to create a new file.

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All you have to do is give a new name to the new file, and that means you will not override the existing

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file.

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So like, that's in right mode.

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S file.

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Five, that's right, modify its contents, execute.

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And this is a new file without a comma.

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And that is the coat.

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Let's try by overwriting the file.

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File three The case we run.

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Now you go to five three doses and you don't see the coma anymore.

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Whether you overrides or creates a new file that that is up to you, I would suggest that if you want

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to override the existing file, perhaps you want to make a copy first, just copy the folder where your

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files are and put it somewhere else just to back it up in case you screw things with Python.

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So that was an example on using file reading and writing.

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In practical example, in the next video, we will remove the comma from multiple files at once.

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So sue there.