Concatenating strings with mathematical symbols in Python 3

Question

I created a dictionary for peoples' names as such:

names = {"first": , "second": , "third":}

What I want to do is call each name and combine them as a string, being separated by a plus sign. Below is a tedious way of doing it:

str(names["first"]) + "+" + str(names["second"]) + "+" + str(names["third"])

This line is from a larger module I am attempting to create. I tried to following for simplicity, but it resulted in a syntax error:

str(names["first"] "%+d" + names["second"] "%+d" + names["third"])

Is there a way of simplifying the above so that it prints:

firstname+secondname+thirdname

Answer 1

In python 2 you have to use the slightly hacky

"{first}+{second}+{third}".format(**names)

However, as GingerPlusPlus points out, in python 3 you can get away from this **kwargs chicanery and instead use format_map

"{first}+{second}+{third}".format_map(names)

Answer 2

如果可以使用namedtuple而不是dict来存储名称，则建议：

'+'.join(map(str, names))