Funtions in Python

 

Defining a Function                                                                                     

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

Syntax

 

def functionname( parameters ): "function_docstring" function_suite return [expression]

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

 

Example

def printme( str ): "This prints a passed string into this function" print (str) return   Calling a Function Defining a function gives it a name, specifies the parameters that are to be included in the function and structures the blocks of code. Once the basic structure of a function is finalized, you can execute it by calling it from another function or directly from the Python prompt. Following is an example to call the printme() function-   #!/usr/bin/python3     # Function definition is here def printme( str ): "This prints a passed string into this function" print (str) return     # Now you can call printme function printme("This is first call to the user defined function!") printme("Again second call to the same function") When the above code is executed, it produces the following result-   This is first call to the user defined function! Again second call to the same function

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