Hi there, in this lecture, you're going to learn how to delete the contents of a txt file, either totally or partially, I have created a new file on my D drive this test dot txt right here. And this file contains some text. Actually a phrase let me show you. Python is the greatest programming language of all time. Do you agree? Now let's head over to the Python interpreter and see how can we remove text from within this file using a special method that Python provides us with?

First of all, let's open the file for reading using the open method as usual. So I'm going to type in F equals open D, colon, double backslash test dot txt. If we check F, we see that it has been open for reading. Okay, now let's use the read method from earlier in the course to see the contents of this file. So F dot read, and indeed we see the phrase that we've just seen. Inside the text file, great.

Now let's also check the number of characters inside this file using the Len function, of course. So Len of F dot read, oops, we got zero characters. Why is that? Well, as you might have already guessed, we already read the entire file using the read method up here. And now the cursor is positioned at the end of the file. Our job is to reposition the cursor at the beginning of the file.

What was the method we used to achieve this? You guessed it, it's the seek method. So let me type in F dot seek of zero. Now let's try using the Len function once again, and it seems that we have 73 characters inside our text file. Okay, now the method to use when you want to delete the contents of a text file is called truncate. So let's try it on our file and see if the text inside gets deleted or not.

So F dot truncate open and close parentheses and And Surprise, surprise, we get an error. Why? Because in order to delete text from the file, we need to also have the file open for writing. But in our case, we only have the file available for reading, which is not enough. Therefore, let's close the file and open it once again for reading and writing at the same time. Okay, so I've got close First of all, and now I'm going to open the file once again, this time using R plus, which means open the file for reading and writing simultaneously.

Okay, great. Now let's try to use the truncate method once again on this file, so f dot truncate. Okay, this time we didn't receive any error, but we did receive this zero right here. This zero means that zero characters are left inside the file after the use of the truncate method. Now let's check if this is indeed correct. Let's go to notepad plus plus and indeed after reloading the file, here it is.

We can Now see that our text is gone. Great job. However, as the beginning of this video, I said that we can either remove the entire content of the file or just a part of it. Let's see how to partially delete the contents inside the file. First of all, let's close our file and re insert the text we previously had. So I'm going to use f close once again, and I'm going to copy the text from up here and into the File, Save.

Okay, next let's open the file once again using the R plus access mode. And now let's truncate this file and leave only the first characters into file and delete the rest of the text. To do that, we just have to enter an integer in between the parentheses of the truncate method. This integer is going to be the number of characters to keep inside the file. So let's say we want the contents of the file to be deleted except the first 10 characters. In this case we will use F dot truncate 10 Ok, now let's also close the file and check the results.

Reload. And as you can see, this time, we only have 10 characters left inside the file. So we have 123456789 and 10. Also, if you want to do this in the Python interpreter, we can open the file once again for reading, and then check the result using the Len function as we did before. So Len of F dot read, the result is the same 10 characters, okay, don't forget to close the file as always, and we got the results we were looking for. So great job again.

I hope this short video has been fun and useful and I will see you in the next one.