Python_%r&%s

%r用rper()方法处理对象
%s用str()方法处理对象


处理一些简单对象时，二者几乎没有差别，比如说处理int型对象
eg1:
print "I am %d years old." % 22  
print "I am %s years old." % 22  
print "I am %r years old." % 22 
结果:
I am 22 years old.  
I am 22 years old.  
I am 22 years old. 


eg2:
另外一些情况两者就不同了
text = "I am %d years old." % 22  
print "I said: %s." % text  
print "I said: %r." % text 
结果:
I said: I am 22 years old..  
I said: 'I am 22 years old.'. // %r 给字符串加了单引号


eg3:
import datetime  
d = datetime.date.today()  
print "%s" % d  
print "%r" % d  
结果:
2014-04-14  
datetime.date(2014, 4, 14)
可见，%r打印时能够重现它所代表的对象(rper() unambiguously recreate the object it represents)