In this Python snippet post we're going to take a closer look at a function we've all been using since we wrote our very first "Hello, World!" in Python. Of course, I'm talking about print.

print actually has a lot of functionality that gets overlooked, and certainly isn't covered in most Python courses. For example, print accepts an arbitrary number of arguments, allowing us to pass in several values to print in one go.

print(1, 2, 3, 4, 5)  # 1 2 3 4 5

Note that this is not the same as us passing in a single tuple of values like this:

print((1, 2, 3, 4, 5))  # (1, 2, 3, 4, 5)

Instead, each value is a separate argument, and items are separated by commas.

By default, print will put a space between each of the items in the print output, but we can configure this using the sep keyword only parameter. sep accepts a string as a value, and this string will be placed between each item in the printed result.

print(1, 2, 3, 4, 5, sep=", ")   # 1, 2, 3, 4, 5
print(1, 2, 3, 4, 5, sep=" | ")  # 1 | 2 | 3 | 4 | 5

print also has another keyword only parameter called end which allows us to configure what gets placed at the end of the print line. The default value is "\\n", which is the newline character. This is why each print function normally prints on a different line.

Perhaps we want a blank line after a particular print. We could achieve this like so:

print(1, 2, 3, 4, 5, sep=" | ", end="\\n\\n")

Here we add two newline characters on the end of the print output. This has the advantage of working with numbers or other types where we can't easily concatenate a newline character.

Another use for end is to remove the line break from the end of the print output, allowing us to leave the cursor on the same line.

The final piece of configuration we're going to look at is the file parameter. The default value for file is sys.stdout, but we have a couple of interesting options available to us.

The first is sys.stderr, which allows us to print a line as though it were an exception. This means that it's coloured red, and therefore stands out from the normal print output.

import sys

print("You messed up!", file=sys.stderr)

Another interesting option is printing to just any old file. In order do do this, we have to use the open function as usual to generate a file object. I'd recommend using a context manager for this:

with open("example.txt", "w") as f:
	print("Here is some file content", file=f)

Generally speaking, you're going to want to use the write method instead for something like this, but print does have the advantage of accepting non-string types, so there are some valid use cases.

Wrapping Up

That's it for this snippet post. I hope you learnt something new, and if you're interested in learning more about print, be sure to check out the official documentation.

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Catch us again on Thursday for another full length post!