%r与%s的区别

%r用rper()方法处理对象

%s用str()方法处理对象

有些情况下，两者处理的结果是一样的，比如说处理int型对象。

例一：

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

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

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

返回结果：

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I am 22 years old.

I am 22 years old.

I am 22 years old.

另外一些情况两者就不同了

例二：

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text = "I am %d years old." % 22

print "I said: %s." % text

print "I said: %r." % text

返回结果：

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I said: I am 22 years old..

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

再看一种情况

例三：

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import datetime

d = datetime.date.today()

print "%s" % d

print "%r" % d

返回结果：

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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)