CODEWITHSUNDEEP
pythonsyntax
OscarRyz
OscarRyz

Reputation: 199215

What's the u prefix in a Python string?

Like in:

u'Hello'

My guess is that it indicates "Unicode", is that correct?

If so, since when has it been available?

Upvotes: 341

Views: 332297

Answers (5)

Chris
Chris

Reputation: 6194

I came here because I had funny-char-syndrome on my requests output. I thought response.text would give me a properly decoded string, but in the output I found funny double-chars where German umlauts should have been.

Turns out response.encoding was empty somehow and so response did not know how to properly decode the content and just treated it as ASCII (I guess).

My solution was to get the raw bytes with 'response.content' and manually apply decode('utf_8') to it. The result was schöne Umlaute.

The correctly decoded

für

vs. the improperly decoded

fĂźr

Upvotes: 8

Stefan Kendall
Stefan Kendall

Reputation: 67802

You're right, see 3.1.3. Unicode Strings.

It's been the syntax since Python 2.0.

Python 3 made them redundant, as the default string type is Unicode. Versions 3.0 through 3.2 removed them, but they were re-added in 3.3+ for compatibility with Python 2 to aide the 2 to 3 transition.

Upvotes: 246

kennytm
kennytm

Reputation: 523214

My guess is that it indicates "Unicode", is it correct?

Yes.

If so, since when is it available?

Python 2.x.

In Python 3.x the strings use Unicode by default and there's no need for the u prefix. Note: in Python 3.0-3.2, the u is a syntax error. In Python 3.3+ it's legal again to make it easier to write 2/3 compatible apps.

Upvotes: 58

Andrew
Andrew

Reputation: 9180

The u in u'Some String' means that your string is a Unicode string.

Q: I'm in a terrible, awful hurry and I landed here from Google Search. I'm trying to write this data to a file, I'm getting an error, and I need the dead simplest, probably flawed, solution this second.

A: You should really read Joel's Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!) essay on character sets.

Q: sry no time code pls

A: Fine. try str('Some String') or 'Some String'.encode('ascii', 'ignore'). But you should really read some of the answers and discussion on Converting a Unicode string and this excellent, excellent, primer on character encoding.

Upvotes: 156

Frank Krueger
Frank Krueger

Reputation: 70983

All strings meant for humans should use u"".

I found that the following mindset helps a lot when dealing with Python strings: All Python manifest strings should use the u"" syntax. The "" syntax is for byte arrays, only.

Before the bashing begins, let me explain. Most Python programs start out with using "" for strings. But then they need to support documentation off the Internet, so they start using "".decode and all of a sudden they are getting exceptions everywhere about decoding this and that - all because of the use of "" for strings. In this case, Unicode does act like a virus and will wreak havoc.

But, if you follow my rule, you won't have this infection (because you will already be infected).

Upvotes: 2

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