简单介绍Python中%r和%s

print "I am %d years old." % 22  
print "I am %s years old." % 22  
print "I am %r years old." % 22

I am 22 years old.  
I am 22 years old.  
I am 22 years old.

text = "I am %d years old." % 22  
print "I said: %s." % text  
print "I said: %r." % text

I said: I am 22 years old..  
I said: 'I am 22 years old.'. // %r 给字符串加了单引号

import datetime  
d = datetime.date.today()  
print "%s" % d  
print "%r" % d

2014-04-14  
datetime.date(2014, 4, 14)