Function Call
The general form of a function call:
function_name(arguments)
The rules for executing a function call:
- Evaluate the arguments.
- 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