%s 表示为字符替代符号
%r 表示为引号+字符替代符号

今日练习。
http://learnpythonthehardway.org/book/ex6.html

x = "There are %d types of people." % 10
binary = "binary"
do_not = "don't"
y = "Those who know %s and those who %s." %(binary,do_not)

print (x)
print(y)


print ("I said: %r." % x)
print("I also said: '%s'" % y)
hilarious = False
joke_evaluation = "Isn't that joke so funny?! %r"

print (joke_evaluation % hilarious)

w = "This is the left side of ..."
e = "a stromg wotj a rogjt side."

print (w + e)