Defining a Function in Python

You can define functions to provide the required functionality. Here are simple rules to define a function in Python.

  • Function blocks begin with the keyword def followed by the function name and parentheses ( ( ) ).
  • Any input parameters or arguments should be placed within these parentheses. You can also define parameters inside these parentheses.
  • The first statement of a function can be an optional statement - the documentation string of the function or docstring.
  • The code block within every function starts with a colon (:) and is indented.
  • The statement return [expression] exits a function, optionally passing back an expression to the caller. A return statement with no arguments is the same as return None.


def functionname( parameters ):
return [expression]

By default, parameters have a positional behavior and you need to inform them in the same order that they were defined.


The following function takes a string as input parameter and prints it on standard screen.

def printme( str ):
"This prints a passed string into this function"
print str