str()一般是将数值转成字符串。
repr()是将一个对象转成字符串显示,注意只是显示用,有些对象转成字符串没有直接的意思。如list,dict使用str()是无效的,但使用repr可以,这是为了看它们都有哪些值,为了显示之用。
The str() function is meant to return representations of values which are fairly
human-readable, while repr() is meant to generate representations which can be read by
the interpreter (or will force a SyntaxError if there is not equivalent syntax). For
objects which don't have a particular representation for human consumption, str() will
return the same value as repr(). Many values, such as numbers or structures like lists
and dictionaries, have the same representation using either function. Strings and
floating point numbers, in particular, have two distinct representations.
Some examples:
>>> s = 'Hello, world.'
>>> str(s)
'Hello, world.'
>>> repr(s)
"'Hello, world.'"
>>> str(0.1)
'0.1'
>>> repr(0.1)
'0.10000000000000001'
>>> x = 10 * 3.25
>>> y = 200 * 200
>>> s = 'The value of x is ' + repr(x) + ', and y is ' + repr(y) + '...'
>>> print s
The value of x is 32.5, and y is 40000...
>>> # The repr() of a string adds string quotes and backslashes:
... hello = 'hello, world
'
>>> hellos = repr(hello)
>>> print hellos
'hello, world
'
>>> # The argument to repr() may be any Python object:
... repr((x, y, ('spam', 'eggs')))
"(32.5, 40000, ('spam', 'eggs'))"
>>> # reverse quotes are convenient in interactive sessions:
... `x, y, ('spam', 'eggs')`
"(32.5, 40000, ('spam', 'eggs'))"
翻译:
Python 有办法将任意值转为字符串:将它传入repr() 或str() 函数。
(如果没有等价的语法,则会发生SyntaxError 异常) 某对象没有适于人阅读的解释形式的话, str() 会返回与repr()
>>> s = 'Hello, world.'
>>> str(s)
'Hello, world.'
>>> repr(s)
"'Hello, world.'"
>>> str(1.0/7.0)
'0.142857142857'
>>> repr(1.0/7.0)
'0.14285714285714285'
>>> x = 10 * 3.25
>>> y = 200 * 200
>>> s = 'The value of x is ' + repr(x) + ', and y is ' + repr(y) + '...'
>>> print s
The value of x is 32.5, and y is 40000...
>>> # The repr() of a string adds string quotes and backslashes:
... hello = 'hello, world
'
>>> hellos = repr(hello)
>>> print hellos
'hello, world
'
>>> # The argument to repr() may be any Python object:
... repr((x, y, ('spam', 'eggs')))
"(32.5, 40000, ('spam', 'eggs'))"