Python3基础 str format 位置参数与关键字参数，,?python :

Python3基础 str format 位置参数与关键字参数，,?python :

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python : 3.7.0OS : Ubuntu 18.04.1 LTS
IDE : PyCharm 2018.2.4conda : 4.5.11type setting : Markdown

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code

coder@Ubuntu:~$ source activate py37(py37) coder@Ubuntu:~$ ipythonPython 3.7.0 (default, Jun 28 2018, 13:15:42) Type ‘copyright‘, ‘credits‘ or ‘license‘ for more informationIPython 6.5.0 -- An enhanced Interactive Python. Type ‘?‘ for help.In [1]: # 位置参数In [2]: "{0}{1}{2}{1}{0}".format("a","b","c")  # "a"填的是{0}   "b"填的是{1} "c"   ...: 填的是2Out[2]: ‘abcba‘In [3]: In [3]: # 关键字参数In [4]: "{var1}{var2}{var3}{var2}{var1}".format(var1="a",var2="b",var3="c")Out[4]: ‘abcba‘In [5]: In [5]: # 混合In [6]: "{0}{var1}{var2}".format("a",var1="b",var2="c")  # 可以这么做，但不推荐Out[6]: ‘abc‘In [7]: In [7]: "{var}{0}".format("a",var="b")Out[7]: ‘ba‘In [8]: exit(py37) coder@Ubuntu:~$ source deactivate py37coder@Ubuntu:~$ 

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addition

    def format(self, *args, **kwargs): # known special case of str.format        """        S.format(*args, **kwargs) -> str                Return a formatted version of S, using substitutions from args and kwargs.        The substitutions are identified by braces (‘{‘ and ‘}‘).        """        pass

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coder@Ubuntu:~$ source activate py37(py37) coder@Ubuntu:~$ ipythonPython 3.7.0 (default, Jun 28 2018, 13:15:42) Type ‘copyright‘, ‘credits‘ or ‘license‘ for more informationIPython 6.5.0 -- An enhanced Interactive Python. Type ‘?‘ for help.In [1]: # 错误的示范In [2]: "{var}{0}".format(var="b","a")  File "<ipython-input-2-ec3e374dcf52>", line 1    "{var}{0}".format(var="b","a")                             ^SyntaxError: positional argument follows keyword argumentIn [3]: exit(py37) coder@Ubuntu:~$ source deactivate py37coder@Ubuntu:~$ 

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resource

[文档] https://docs.python.org/3/[规范] https://www.python.org/dev/peps/pep-0008/[规范] https://zh-google-styleguide.readthedocs.io/en/latest/google-python-styleguide/python_language_rules/[源码] https://www.python.org/downloads/source/[ PEP ] https://www.python.org/dev/peps/[平台] https://www.cnblogs.com/

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每种语言都有独特的思想，初学者需要转变思维、踏实践行、坚持积累。

Python3基础 str format 位置参数与关键字参数