A008： str函数和repr函数的区别

str()一般是将数值转成字符串。（方便人看）

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。
（方便机器看）

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.

参考： http://www.guokr.com/post/91890/