Python % operator vs concatenation

Question

When would it be preferable to use:

for n in range(0, 100):
    print "The count is "+str(n)

Vs.

for n in range(0, 100):
    print "The count is %d" % (n)

Or visa versa?

[link](http://stackoverflow.com/questions/5082452/python-string-formatting-vs-format). Do you need only such simple substitution like that? — Anton Protopopov, Feb 10 '16 at 05:39
The first one will never be preferable. The creation of temporaries will make it slow. — Paul Rooney, Feb 10 '16 at 05:50
`format` is the more general-purpose solution and code is cleaner, easier to read and more maintainable if you do the same type of things the same way. Doesn't casting and adding white space by concatenation look clunky? — tdelaney, Feb 10 '16 at 05:51

score 1 · Accepted Answer · edited Feb 10 '16 at 06:01

The %d syntax has been deprecated. Use str.format for string formatting.

Examples:

"My name is {0}.".format("Austin")
"I am {} years old and make ${:.2f} per hour.".format(50, 50.29999) # positional arguments
myDict = { "language" : "English", "major" : "Computer Networking" }
"I speak {language} and have a degree in {major}.".format(**myDict)
myList = [2, "German Sheppard", "Lucy", "Ethel" ]
"I own {} {}s named '{}' and '{}'.".format(*myList)

Python % operator vs concatenation

1 Answers1