Reversing a string
Jan Vorwerk
jan.vorwerk at cretin.fr
Wed Jul 4 17:46:02 EDT 2007
Martin Durkin a écrit , le 02.07.2007 06:38:
> This is an interesting point to me. I am just learning Python and I
> wonder how I would know that a built in function already exists?
> At what point do I stop searching for a ready made solution to a
> particular problem and start programming my own function?
> Is it just a matter of reading *all* the documentation before I start
> coding?
The answer from another beginner like me is: dir()
Try it out interactively (my example with Python 2.4):
---------------------------------------
>>> dir()
['__builtins__', '__doc__', '__name__']
>>> __builtins__
<module '__builtin__' (built-in)>
>>> dir(__builtins__)
['ArithmeticError', 'AssertionError', 'AttributeError',
'DeprecationWarning', 'EOFError', 'Ellipsis', 'EnvironmentError',
'Exception', 'False', 'FloatingPointError', 'FutureWarning', 'IOError',
'ImportError', 'IndentationError', 'IndexError', 'KeyError',
'KeyboardInterrupt', 'LookupError', 'MemoryError', 'NameError', 'None',
'NotImplemented', 'NotImplementedError', 'OSError', 'OverflowError',
'OverflowWarning', 'PendingDeprecationWarning', 'ReferenceError',
'RuntimeError', 'RuntimeWarning', 'StandardError', 'StopIteration',
'SyntaxError', 'SyntaxWarning', 'SystemError', 'SystemExit', 'TabError',
'True', 'TypeError', 'UnboundLocalError', 'UnicodeDecodeError',
'UnicodeEncodeError', 'UnicodeError', 'UnicodeTranslateError',
'UserWarning', 'ValueError', 'Warning', 'ZeroDivisionError', '_',
'__debug__', '__doc__', '__import__', '__name__', 'abs', 'apply',
'basestring', 'bool', 'buffer', 'callable', 'chr', 'classmethod', 'cmp',
'coerce', 'compile', 'complex', 'copyright', 'credits', 'delattr',
'dict', 'dir', 'divmod', 'enumerate', 'eval', 'execfile', 'exit',
'file', 'filter', 'float', 'frozenset', 'getattr', 'globals', 'hasattr',
'hash', 'help', 'hex', 'id', 'input', 'int', 'intern', 'isinstance',
'issubclass', 'iter', 'len', 'license', 'list', 'locals', 'long', 'map',
'max', 'min', 'object', 'oct', 'open', 'ord', 'pow', 'property', 'quit',
'range', 'raw_input', 'reduce', 'reload', 'repr', 'reversed', 'round',
'set', 'setattr', 'slice', 'sorted', 'staticmethod', 'str', 'sum',
'super', 'tuple', 'type', 'unichr', 'unicode', 'vars', 'xrange', 'zip']
>>> reversed
<type 'reversed'>
>>> dir(reversed)
['__class__', '__delattr__', '__doc__', '__getattribute__', '__hash__',
'__init__', '__iter__', '__len__', '__new__', '__reduce__',
'__reduce_ex__', '__repr__', '__setattr__', '__str__', 'next']
>>> print reversed.__doc__
reversed(sequence) -> reverse iterator over values of the sequence
Return a reverse iterator
---------------------------------------
Far from me the idea that manuals are useless, but this is a nice thing
about Python that you can look at what is available interactively.
Cheers
Jan
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