Funtions

What are Python Functions?

A function is a collection of related assertions that performs a mathematical, analytical, or evaluative operation. Python functions are simple to define and essential to intermediate-level programming. The exact criteria hold to function names as they do to variable names. 
Advantages:

• By including functions, we can prevent repeating the same code block repeatedly in a program.
• Python functions, once defined, can be called many times and from anywhere in a program.
• If our Python program is large, it can be separated into numerous functions which is simple to track.
• The key accomplishment of Python functions is we can return as many outputs as we want with different arguments.
• 
  

Syntax of Python Function

1. def name_of_function( parameters ):  

1.     """This is a docstring"""  

1.     # code block  

def square( num ):  

    """ 

    This function computes the square of the number. 

    """  

    return num**2   

object_ = square(9)  

print( "The square of the number is: ", object_ )

Output:

The square of the number is:  81

=================================================================

Calling a Function

A function is defined by using the def keyword and giving it a name, specifying the arguments that must be passed to the function, and structuring the code block.

Code:

# Defining a function  
def a_function( string ):  
    "This prints the value of length of string"  
    return len(string)  
 

# Calling the function we defined  

print( "Length of the string Functions is: ", a_function( "Functions" ) )  
print( "Length of the string Python is: ", a_function( "Python" ) ) 

Output:

Length of the string Functions is:  9
Length of the string Python is:  6

=================================================================

Pass by Reference vs. Value

Code:

# defining the function  

def square( my_list ):  

    '''''This function will find the square of items in list'''  

    squares = []  

    for l in my_list:  

        squares.append( l**2 )  

    return squares  

  

# calling the defined function  

list_ = [45, 52, 13];  

result = square( list_ )  

print( "Squares of the list is: ", result )  

Output:

Squares of the list is:  [2025, 2704, 169]