What is the difference between %i and %d in Python?

Question

OK I was looking into number formatting and I found that you could use %d or %i to format an integer. For example:

number = 8
print "your number is %i." % number

or

number = 8
print "your number is %d." % number

But what is the difference? I mean i found something but it was total jibberish. Anyone speak Mild-Code or English here?

Python uses the C conventions here, the same answer applies. — Martijn Pieters, Jul 16 '13 at 15:06
If you ever want to upgrade to python 3, I recommend getting into the habit of using parens around the print body, since print is a function in python 3. — beatgammit, Jul 16 '13 at 15:09
@MartijnPieters I don't really understand that though. I was looking a bit for more English lol — , Jul 16 '13 at 15:12
RTFM on format specifiers. They're the same. What part of "signed integer decimal" don't you understand? — martineau, Jul 16 '13 at 15:13
@malcolmk181: sure, an english language explanation is added below. — Martijn Pieters, Jul 16 '13 at 15:15
not really a duplicate this is a question about python the one marked as identical is explicitly a c++ question. sometimes stack overflow is weird. — eric, Apr 21 '19 at 15:53

score 21 · Accepted Answer · edited May 23 '17 at 10:30

21

Python copied the C formatting instructions.

For output, %i and %d are the exact same thing, both in Python and in C.

The difference lies in what these do when you use them to parse input, in C by using the scanf() function. See Difference between format specifiers %i and %d in printf.

Python doesn't have a scanf equivalent, but the Python string formatting operations retained the two options to remain compatible with C.

The new str.format() and format() format specification mini-language dropped support for i and stuck with d only.

edited May 23 '17 at 10:30

Community

answered Jul 16 '13 at 15:15

Martijn Pieters

OK thanks, that's a bit easier to understand :) – Jul 16 '13 at 15:18
The new format specification mini-language may have dropped `i`, but it added `n`, which is almost as the same as `i` except it's locale-aware number separator-wise. – martineau Jul 16 '13 at 15:19
@martineau: Which means it is *not* the same thing as `d`. `i` *is* the same as `d`. – Martijn Pieters Jul 16 '13 at 15:19
@Martijn: Sorry, my mistake, I meant to say "`n` is almost the same as `d` except...". – martineau Jul 16 '13 at 15:25

score 3 · Answer 2 · answered Jul 16 '13 at 15:14

3

No difference.

And here's the proof.

The reason why there are two is that, %i is just an alternative to %d ,if you want to look at it at a high level (from python point of view).

Here's what python.org has to say about %i: Signed integer decimal.

And %d: Signed integer decimal.

%d stands for decimal and %i for integer.

but both are same, you can use both.

answered Jul 16 '13 at 15:14

tenstar

@malcolmk i have answered and reasoned why there are 2 choices – tenstar Jul 16 '13 at 15:18
Seems reasonable, but we'll never know for sure since it would require the ability to read minds in the past... – martineau Jul 16 '13 at 15:27

score 2 · Answer 3 · answered Jul 16 '13 at 15:08

2

answered Jul 16 '13 at 15:08

Sven

There's gotta be a reason though right? – Jul 16 '13 at 15:14
The string output formatting in Python is obviously inspired by C. Martijn Pieters pointed you in the right direction already: [Difference between format specifiers %i and %d in printf](http://stackoverflow.com/questions/1893490/difference-between-format-specifiers-i-and-d-in-printf) – Sven Jul 16 '13 at 15:19

3 Answers3