A Short notes on Python Programming
Function Call
The general form of a function call:
function_name(arguments)
The rules for executing a function call:
1. Evaluate the arguments.
2. Call the function, passing in the argument values.
Terminology:
- Argument: a value given to a function
- Pass: to provide to a function
- Call: ask Python to evaluate a function
- Return: pass back a value
Example function calls:
>>> abs(-23)
23
>>> abs(56.24)
56.24
Function dir
Python has a set of built-in
functions. To see the list of built-in functions, run dir(__builtins__)
:
>>>
dir(__builtins__)< br/> ['ArithmeticError', 'AssertionError',
'AttributeError', 'BaseException', 'BufferError', 'BytesWarning',
'DeprecationWarning', 'EOFError', 'Ellipsis', 'EnvironmentError', 'Exception',
'False', 'FloatingPointError', 'FutureWarning', 'GeneratorExit', 'IOError',
'ImportError', 'ImportWarning', 'IndentationError', 'IndexError', 'KeyError',
'KeyboardInterrupt', 'LookupError', 'MemoryError', 'NameError', 'None',
'NotImplemented', 'NotImplementedError', 'OSError', 'OverflowError',
'PendingDeprecationWarning', 'ReferenceError', 'ResourceWarning',
'RuntimeError', 'RuntimeWarning', 'StopIteration', 'SyntaxError',
'SyntaxWarning', 'SystemError', 'SystemExit', 'TabError', 'True', 'TypeError',
'UnboundLocalError', 'UnicodeDecodeError', 'UnicodeEncodeError',
'UnicodeError', 'UnicodeTranslateError', 'UnicodeWarning', 'UserWarning',
'ValueError', 'Warning', 'ZeroDivisionError', '_', '__build_class__',
'__debug__', '__doc__', '__import__', '__name__', '__package__', 'abs', 'all',
'any', 'ascii', 'bin', 'bool', 'bytearray', 'bytes', 'callable', 'chr',
'classmethod', 'compile', 'complex', 'copyright', 'credits', 'delattr', 'dict',
'dir', 'divmod', 'enumerate', 'eval', 'exec', 'exit', 'filter', 'float',
'format', 'frozenset', 'getattr', 'globals', 'hasattr', 'hash', 'help', 'hex',
'id', 'input', 'int', 'isinstance', 'issubclass', 'iter', 'len', 'license',
'list', 'locals', 'map', 'max', 'memoryview', 'min', 'next', 'object', 'oct',
'open', 'ord', 'pow', 'print', 'property', 'quit', 'range', 'repr', 'reversed',
'round', 'set', 'setattr', 'slice', 'sorted', 'staticmethod', 'str', 'sum',
'super', 'tuple', 'type', 'vars', 'zip']
Function help
To get information about a
particular function, call help
and pass the function as the argument. For
example:
>>> help(abs)
Help on built-in function abs in module builtins:
abs(...)
abs(number) -> number
Return the absolute value of the argument.
Optional arguments
In the description of function pow
below, the square brackets around [, z]
indicate that the third argument is
optional:
>>> help(pow)
Help on built-in function pow in module builtins:
pow(...)
pow(x, y[, z]) -> number
With two arguments, equivalent to x**y. With three arguments,
equivalent to (x**y) % z, but may be more efficient (e.g. for longs).
Function pow
can be called with either two or three
arguments:
>>> pow(2, 5)
32
>>> pow(2, 5, 3)
2