Best way to concatenate short strings in Python

Question

For example, if I'm just printing out an error, is it better to do

print "Error encountered: " + error.args[0]

or

print ''.join("Error encountered: ", error.args[0])

or perhaps

print "Error encountered: {0}".format(error.args[0])

Which one would be the fastest, and which would be the most "Pythonic" way to do it?

For "fastest", you need to just try it. I suspect it'll be quite close and may even depend on the particular implementation — John La Rooy
– John La Rooy, Commented Jul 8, 2013 at 4:20

John La Rooy · Accepted Answer · 2013-07-08 04:15:14Z

4

This is generally the best way

print "Error encountered: {0}".format(error.args[0])

When you need to internationalise you application, you can often just go

print _("Error encountered: {0}").format(error.args[0])

And let gettext to the rest of the work

If there are multiple argumnent's it's best to use the mapping version

print _("Error encountered: {err}").format(err=error.args[0])

So it'll still work if a translation needs to move the order of the arguments around

answered Jul 8, 2013 at 4:15

John La Rooy

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falsetru · Accepted Answer · 2013-07-08 04:03:33Z

2

No need to concatenate strings. Just print them.

print "Error encountered:", error.args[0]

answered Jul 8, 2013 at 4:03

falsetru

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1 Comment

user2357112 Over a year ago

@ron975: Note that the print statement prints a space between consecutive arguments. This is not always what you want.

CaitlinG · Accepted Answer · 2013-07-08 04:31:52Z

0

You could concatenate two strings using several different techniques:

str1 = 'Hello'
str2 = 'there!'

print (str1, str2)

The use of the comma between variables in a print statement automatically inserts a space between the items that are output. If you had used a plus sign, i.e., print (str1 + str2), the above output would look like 'HelloWorld'.

Hope this helps.

Caitlin

answered Jul 8, 2013 at 4:31

CaitlinG

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4 Comments

John La Rooy Over a year ago

The OP is using Python2 - we can tell since print is being used as a statement. This is the Python3 version of @falsetru's answer

CaitlinG Over a year ago

Ah, yes. I noticed that. Wouldn't the syntax I used apply to Python 2 as well though?

John La Rooy Over a year ago

Just try it. You'll see that it prints the 2-tuple instead of just the two strings.

John La Rooy Over a year ago

You can use from __future__ import print_function though

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