python中%r和%s的区别

%r用rper()方法处理对象 %s用str()方法处理对象

有些状况下，二者处理的结果是同样的，好比说处理int型对象。 例一：

''' 遇到问题没人解答？小编建立了一个Python学习交流QQ群：857662006 寻找有志同道合的小伙伴，互帮互助, 群里还有不错的视频学习教程和PDF电子书！ '''
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.  
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另一些状况二者就不一样了 例二：

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

I said: I am 22 years old..  
I said: 'I am 22 years old.'. // %r 给字符串加了单引号  
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再看一种状况 例三：

''' 遇到问题没人解答？小编建立了一个Python学习交流QQ群：857662006 寻找有志同道合的小伙伴，互帮互助, 群里还有不错的视频学习教程和PDF电子书！ '''
>> from datetime import datetime 
>> timeinfo = datetime.today()

>> timeinfo
datetime.datetime(2016, 6, 7, 21, 17, 34, 925488)
>> type(timeinfo)
datetime.datetime

>> repr(timeinfo)
'datetime.datetime(2016, 6, 7, 21, 17, 34, 925488)'
>> str(timeinfo)
'2016-06-07 21:17:34.925488'

%r会将后面给的参数原样打印出来，带有类型信息。
formatter = "%r %r %r %r"
 
print formatter % (1, 2, 3, 4)
print formatter % ("one", "two", "three", "four")
print formatter % (True, False, False, True)
print formatter % (formatter, formatter, formatter, formatter)
print formatter % (
"I had this thing.",
"That you could type up right.",
 "But it didn't sing.",
 "So I said goodnight."
 )
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输出结果：

$ python ex8.py
1 2 3 4
'one' 'two' 'three' 'four'
True False False True
'%r %r %r %r' '%r %r %r %r' '%r %r %r %r' '%r %r %r %r'
'I had this thing.' 'That you could type up right.' "But it didn't sing." 'So I said goodnight.'
$
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