With open(file) as: Question [SOLVED]

Python Help
1

Hello,

I have a question regarding the with open as context manager when opening a .txt file.

I have a file with the following contents:

Hello there!

Is everyone ok today?

Let’s get started.

To open the file, I use the following script:

from pathlib import Path

FILE_PATH = Path('/Users/my_pc/Desktop/tester.txt')

with open(FILE_PATH, "r", encoding = 'UTF-8') as f:

    for line in f:
        print(line, end='')  # Prints as per the file
        # print(line)            # Adds two empty lines between text lines

As noted per the comments, depending on which print statement that I use, it either prints as is or it adds two extra empty lines between text lines. Why does it add two extra text lines when using the second print option?

2

When iterating over a file, it’ll yield each line, including the line’s line ending.

print will, by default, print a newline at the end of what it prints.

Therefore, this:

with open(CSV_FILE_PATH, "r", encoding = 'UTF-8') as f:
    for line in f:
        print(line)

will print each line with its line ending and then print a newline.

1 Like
3

Ahh, got it! I see.

Still, I think that Python should read it as entered in the original file. In any case, the extra end='' is no biggie.

Thank you for clearing that up.

Much appreciated.

4

Python does read the lines as they are in the file. Sometimes you want to keep the line endings, other times you don’t, so it’s better to keep them and let you remove them if you don’t want them.

5

Ok, that is if one iterates using a for loop statement to read each line one at a time so as not to overburden memory at once. But if there are no memory constraints, I suppose one can just use the following to read the file contents in one reading (no for loop) :

    text = f.read()
    print(text)
6

Which prints the file content plus one extra line.
You would still need the end=‘’ to copy the text without add ab extra line.

1 Like
7

A better design of print() is that it prints whatever was asked to print only, no more, no less. Why to predict the next printing is going to start a new line or not? Let each print() do its own business.

8

If you want sys.stdout.write, you know where to find it. :slight_smile:

1 Like
9

It’s not a prediction. print is designed to do this, because it’s a useful thing to do. That’s the same reason that you can give it multiple things to print, and it will put spaces in between (and you can disable the spaces using sep, the same way that you would disable the newline using end). It’s also the same reason that it accepts non-string inputs and converts them for you.

If you want the lower-level interface, “here is one string, write it out without changing or adding anything” - that is sys.stdout.write, as Chris says. It works because the standard output is available as sys.stdout, and that output stream is just like a text file open for writing (except there is no actual file on disk).

1 Like
10

OK, I agree with you. print() was designed to ease its most usage cases and, for those rare situation, it let user to disable the extra stuff it had put in. Thank you for providing a different viewing angle of this design.