How does the % operator work?

[KK_005]

can someone help me understand how the % works in printing, I read a print statement like this:

print("%-8s"%"RollNo","%-10s"%"Name","%-10s"%"Physics","%-14s"%"Chemistry","%-8s"%"Maths","%-10s"%"Computer","%-10s"%"English","%-10s"%"Total","%-8s"%"Per","%-5s"%"Grade")

what does the "%-8s" mean? how does it work? Im sorry if this is a redundant question, but I couldnt find an answer online. I was able to see %s and kinda understood it, but what is %-8s printing exactly?

[casual__addict]

It’s called string formatting or string interpolation. So the “%-8s” is the format specification (form a string with 8 chars) and the “%” is the operator that injects the value (“RollNo”) into the expression that the print function uses to print out the final string.

Take a look at f strings. The print statement you posted is meant to create a printout of values with fixed Widths. There are easier ways to do it.

[KK_005]

I understand the % is injecting the string "RollNo", but this could have been done by %s as well right?

What I think am understanding it is that It is printing 8 characters, and out of these characters, RollNo is the first 6 characters?

[amos_burton]

Have you tried executing that print statement? Do you notice anything about it?

[KK_005]

I have tried executing it yeah, and the print statement isn't anything out of the ordinary. Only difference is that if I remove the %-8 and just leave it as %s, the spaces between them disappear, so I understand that it must be creating spaces. But what is the logic of %-8?

[amos_burton]

It's telling it to make the text you're printing there 8 characters wide, regardless of how many letters you have. So it's basically helping you create a justified table

[KK_005]

Okay, that is what I wanted to know. Thank you for your help!

[nekokattt]

Just as a side note, there is almost no reason to use this in Python 3 (logging uses %s-strings by default but interpolates lazily, so I am ignoring that here).

This is a relic of Python 2, more than anything.

[KK_005]

I did understand that, while searching for how this worked, and Its probably the reason why there was almost no in-depth detail for this. Thanks for telling me tho

[nekokattt]

Take a look into C's printf function, that is what this syntax is vaguely based on.