So what if you want your date and time in a certain format,

like you need to print that out all pretty for a script or on your blog.

Welcome to the warm, wonderful world of date formatting.

I've put a link in the teacher's notes.

You should probably have this open for the video and the later code challenges.

Trust me, no one memorizes this.

But complicated or not, it's one of the most useful areas in the datetime library.

So as you can see, I jumped ahead a little bit.

I've already got datetime imported and I've already created our now variable.

Just like we did in the last video.

So lets look at our object once again.

We get this datetime.datetime which tells us the class and everything and

then we get this spelled out big long thing of year,

month, day, hour, minute, second, microsecond.

It's definitely readable, but do we wanna look at that every single time?

Do we have to look at that every single time?

Do we have to pull apart the month and

the year attributes in order to get out our, you know, nice, pretty strings?

No, of course we don't.

Python's not gonna make us do all that extra work.

So let's look at this function called strftime.

strftime let's us turn a date, a time, or

a datetime into a string formatted how we want.

So let's use strftime and let's get out just the month name and the day number.

So we do now.strftime, and then we have to pass in a string.

So %B is the month name.

I'm gonna do a space and I'm gonna %d.

And print that and we get October 15th.

So that's handy enough but there's a problem.

And the problem is that I don't know all of these strings.

So let's come down here and let's actually go to

docs.python.org as we do, and let's search over here for datetime.

And here's our datetime module, and if we look down here,

we have this strftime and strptime behavior.

And there's this awesome, awesome table here showing me everything.

So you can see I did %B, and I got the full name in my current local.

So if I was in Germany, I'd get a different name.

If I was in Spain, I'd get a different name, so on and so forth.

Since I'm in the US, I get January, February, whatever.

Okay, so what I want is I want what we consider like a US

standard time stamp, which is one where it's month, day, year.

Okay.

So now.strftime, and I have to pass in a string.

So let's find month.

Here it is.

Month as zero-padded decimal number.

So that's %m, okay, %m.

And I'm gonna do a slash and I'm gonna do %d is the day.

Cuz I did that before and then now I want the year.

And I want, well, so let's see.

We have here year without century so we get like 01 or

14 which is what we're gonna get.

Or year with century and we'd get a longer number like 2013, 2014.

Let's do the shorter number.

And we're going to do %y.

[NOISE] We press Return and we get 10/15/14.

All right, so that's it.

The hardest part of this is really referring back to those datetime docs.

Finding exactly which one you want in this table is not always the easiest thing.

Sometimes it takes a little bit of reading to figure out which one that you're doing.

So bookmark this, keep it handy, you're gonna be using this a lot.

It's definitely a very, very useful thing to have around.

I mentioned that we're also gonna talk about an strptime function.

Now sadly, strftime and strptime are nearly identical.

There's one letter difference, F or P.

So, you're probably gonna end up confusing them.

I know I do.

But I've started thinking of them in this way, strftime is string from time,

or string formatted time.

And strptime is string parsed into time.

So, hopefully that pneumonic, depending on how good it is, will help you.

So what does strptime do?

I keep saying it, we keep talking about it, but

we haven't talked about what it does yet.

So it let's us make a datetime from a string with a certain format.

Okay, so, let's do this.

Let's say birthday, datetime.strptime and

then we pass in a string that represents the date.

So let's do 2015-04-21.

Which would be the 21st of April next year.

This isn't my birthday, just a random date.

All right, so, but now what I have to do is I have to explain

to datetime how this string is formatted.

And I do that with the same string types that we used in strftime.

So, I remember that %Y is the year.

Let's look that up just to make sure, and there it is.

That's the long year.

Okay.

And then we do hyphen and we do %m, hyphen, %d, all right.

So the only thing different here is kind of the order they're in, and

we used a cap Y instead of a lower case Y.

Oh, sorry, it is datetime.datetime.

[BLANK_AUDIO]

And I missed my dot.

There we go, okay.

So now, we should be able to look at birthday and

there's our datetime that was created.

Now, you notice there's no there's no hours on this because we didn't have any

hours specified in our strptime.

But that only had the date.

What if we wanted to include a time as well?

So let's do birthday_party.

Because this is when the party is.

So datetime.datetime.strptime.

And we'll do 2015 again, and 04 again, and 21.

And then we'll do a space, and then we'll do 09, colon, 00.

Okay, so this is a lot more to explain.

We're having the birthday party, you know what?

Let's have the birthday party at noon instead.

All right, how do we describe this one?

Well, the beginning is still the same.

So it's that. And then we put in a literal space.

And then I need hours.

And, let's see.

Hours are capital H, all right.

Capital H, colon, and I know that capital M is minutes.

You start to memorize some of these as you go through.

And now let's look at birthday_party.

And there's our time and it's set at noon.

All right, so we have everything we put in there.

Now, I want you to notice, I did the capital H so it's a 24-hour clock.

So like 1 PM would be 13, 6 PM would be 18.

I do that so I don't have to specify AM or PM.

There is a flag you can put in for AM and PM if you wanna use those,

if that's more comfortable to you.

So you have full control of this.

Turning datetime objects into strings, or strings into datetimes,

is mostly a matter of remembering or looking up the format strings.

I'm sure you can see it's also pretty handy.

Actually, I have a challenge for you now.

Using the Python docs, and strftime and

strptime, make a script that accepts a month and

day date in whatever format you want that returns a link to Wikipedia for that date.

Be sure you tell the user how to format their data for you.

Come back in the next video and we'll build it together.