python中%r和%s的区别

た入场券 2023-01-23 11:53 188阅读 0赞

%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：**

print ("I am %d years old." % 22)
    print ("I am %s years old." % 22)  
    print ("I am %r years old." % 22)
    
    #输出：
    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)  
    
    #输出：
    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：**

>> from datetime import datetime 
    >> timeinfo = datetime.today()
    
    >> timeinfo
    datetime.datetime(2020, 1, 1, 1, 17, 34, 925488)
    >> type(timeinfo)
    datetime.datetime
    
    >> repr(timeinfo)
    'datetime.datetime(2020, 1, 1, 1, 17, 34, 925488)'
    >> str(timeinfo)
    '2020-01-01 01:17:34.925488'

%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."
     ))
    
    #输出：
    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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