Understanding Python Functions: Day 16 Summary

Introduction :

Welcome back to my Python journey! Yesterday, I laid the foundation with control structures in python.

Today, I dove into Functions, Let's explore what I learned!

core python :

1. introduction

2. operators

3. data types

4. control structure

5. control statement

6. FUNCTION :

~~~~ WHAT IS FUNCTION \~~~ .

function is collection of expression and statements.

HOW TO DEFINE A FUNCTION IN PYTHON

• . to define a function in python def keyword we have to use.

• . to define the body of a function in python INDENTATION mechanism will be used.

• . to define empty body we can use pass control statement.

. syntax :

def FunctionName ( ) :

body

. syntax :

def FunctionName ( ) :

pass

. the name which is used to represent a function is known as IDENTIFIER.

. function name is depends on user as per the demand of situation.

example :

def Test() : #definition

print ("i am fun")

MAIN FUNCTION IN PYTHON ~

• . in c cpp java program starts execution from main function.

• . main function defination is compulsory in c cpp java.

• . main is a special function in c cpp java.

• . in python main is an ordinary function.

• . in python program does not starts execution from main.

• . main function defination is not compulsory in python.

HOW TO EXECUTE A FUNCTION IN PYTHON ( HOW TO CALL ) :

• . function definition is not sufficient to execute a function.

• . to execute a function, with definition, call is required.

• . until function is not called, that function is not going to execute.

• . FUNCTION def MUST BE AVALIABLE BEFORE THE FUNCTION CALL, due to python is an interpreted programming language.

. if we call a function N times that function will execute N times.

example :

def Test() : #defination

print ("i am fun")

Test () #calling

CONTROL FLOW DURING FUNCTION DEF AND CALL ~~~~~~~~~~

def main () : # stmt-1

print ( 'i am main !') # stmt-2

bbsr () # stmt-3

def bbsr () : # stmt-4

print ( 'i am bbsr !') # stmt-5

main () # stmt-6

CONTROL FLOW : Statement 1 -> 4 -> 6 -> 2 -> 3 -> 5

while working with function variable is basically two types in python,

• . GLOBAL VARIABLE

• . LOCAL VARIABLE

GLOBAL VARIABLE : ~

• . if a variable is not belongs to any function that var is known as global var.

• . global var is not belongs to any function but any function can enjoy global var.

var = 10
def main () :
        print ( 'i am main enjoying ' , var )
        bbsr ()
def bbsr () :
        print ( 'i am bbsr enjoying ', var )

• . any function can enjoy global var, but can not modify the global var.

• . if we try to modify the global var from a function it will raise UnboundLocalError exception.

var = 10
def main () :
        var = var + 10  # modify the global data  
        print ( 'i am main enjoying ' , var )
        bbsr ()
def bbsr () :
        print ( 'i am bbsr enjoying ', var )

1. . to avoid UnboundLocalError exception while modifying the global var we have use global keyword.

2. . if a function modified the global var that modification is going to reflect in other function also.

var = 10
def main () :
        global var
        var = var + 10  # modify the global data  
        print ( 'i am main enjoying ' , var )
        bbsr ()
def bbsr () :
        print ( 'i am bbsr enjoying ', var )

LOCAL VARIABLE : ~

• . the var which is belongs to a function is known as local var.

• . local var of a function can only be enjoyed in that function where it is local, not from other function.

• . if we try to enjoy the local var of a function in another function it will raise NameError exception.

Example :

def main () :
        var = 10
        print ( 'i am main enjoying ', var )
        bbsr ()
def bbsr () :
        print ( 'i am bbsr enjoying ', var )
main ()

• . to avoid NameError exception while enjoying the local var of one function in another function there are two different mechanisms are avaliable in python,

• . GLOBAL KEYWORD MECHANISM

• . ARGUMENT OR PARAMETER MECHANISM ( most preferable )

global keyword mechanism

def main () :
        global var
        var = 10
        print ( 'i am main enjoying ', var )
        bbsr ()
def bbsr () :
        print ( 'i am bbsr enjoying ', var , 'by global keyword mechanism !')

main ()

argument or parameter mechanism

def main () :
        var = 10
        print ( 'i am main enjoying ', var )
        bbsr ( var )
def bbsr ( var ) :
        print ( 'i am bbsr enjoying ', var , 'by argument or param mechanism!')

main ()

Challenges :

1. Understanding global and local variable.

2. Handling errors.

Resources :

1. Official Python Documentation: Functions

2. W3Schools' Python Tutorial: Functions

3. Scaler's Python Course: Functions

Goals for Tomorrow :

1. Explore something more on Functions.

   Conclusion :

Day 16’s a success!

What are your favorite Python resources? Share in the comments below.

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LinkedIn : [ https://www.linkedin.com/in/archana-prusty-4aa0b827a/ ]

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Share your own learning experiences or ask questions in the comments.

HAPPY LEARNING!!

THANK YOU!!