Python Function

 

PYTHON FUNCTION

PYTHON FUNCTIONS

 

SYNTAX OF USER DEFINED FUNCTION :

def function_name(parameters):

          """docstring"""

         statement(s)

 

HOW FUNCTION WORKS IN PYTHON ?

def functionname():

. . .     .  .    .  .  .

. . .     .  .    .  .  .

 

                                      . . .     .  .    .  .  .

                                        . . .     .  .    .  .  .

 

functionname();

                                         . . .     .  .    .  .  .

                                         . . .     .  .    .  .  .

 

 

EXAMPLE

def  welcome_func(name):

"""this function welcomes to

the person passed in as

parameter """

    printf("hello ," +name +".good morning !")

 

FUNCTION CALL

>>> welcome_func('ram')

hello , ram . good morning !

 

EXAMPLE #1                                                                                                        

program to find the square value of a number using UDF function

#function to find the square value of a number

def sample(a) :

        c=a*a

        return (c)

 

#function call

n=int(input("enter a number:"))

res=sample(n)

print("the square value of %d is %d "%(n,res))

 

OUTPUT

enter a number : 5

the square value of 5 is 25

 

SCOPE AND LIFETIME OF VARIABLES

 

def my_func();

         x=10

        print("value inside function :",x)

 

x=20

my_func()

print("value outside function : ",x)

 

OUTPUT

value inside fulnction : 10

value outside function : 20

 

PYTHON   FUNCTION  ARGUMENTS

VARIABLE FUNCTION ARGUMENTS

PYTHON DEFAULT ARGUMENTS

 

def welcome_func(name , msg = "good morning !"):

"""

this function welcomes to

the person with the

provided message .

 

if messege is not provided,

it defaults to "good morning!"

"""

        print ("hello",name + ','+msg)

welcome_func("kumerasan")

welcome_func("prakash", "have a nice day")

 

PYTHON KEYWORD ARGUMENTS

#example for keyword argument

def welcome_func(name,msg):

                print("hai",name,msg)

name="karthick"

welcome_func(name="karthick",msg="have a nice day")

welcome_func(msg = "have a nice day",name="karthick")

welcome_func(name,msg="have a nice day")

 

OUTPUT

hai karthick have a nice day

hai karthick have a nice day

hai karthick have a nice day

 

PYTHON ARBITARY ARGUEMENTS

def arb_func(*names):

"""this function welcomes all

the person in the names tuple."""

#names is a tuple with arguements

    for na in names :

          print("hello",na)

arb_func("priyadharshini","radhika","samantha","jheevikha")

 

OUTPUT

hello priyadharshini

hello radhika

hello samantha

hello jheevikha

 

PYTHON RECURSION

PYTHON RECURSIVE FUNCTION

 Function call itself is called Recursive Function

#an example of a recursive function to

#find the factorial of a number

 

def calc_factorial(x):

"""this is a recursive function

to find the factorial of an integer """

    if x==1:

        return 1

    else:

        return (x*calc_factorial(x-1))

num=4

print("the factorial of ",num,"is",calc_factorial(num))

 

PYTHON ANONYMOUS / LAMBDA FUNCTIONS

LAMBDA FUNCTIONS

 Anonymous Function are also called Lambda Function.

Lambda functions can have any number of argument but only one Expression.

EXAMPLE OF LAMBDA FUNCTIONS

#program to show the use of lambda functions

double = lambda x:x * 2

#output: 10

print(double(5))

 

f= lambda x,y:x+y

print(f(5,1))

is nearly the same as

def sumtwo(x,y):
return(x+y)

print(sumtwo(5,1))

 

#example for arithemetic operation of two number

In python we can use already saved files by using import module filename

#saved the file in the name of jksample.py

def jkaddition(x,y):
    a=x+y

    return(a)

def jksubtraction(x,y):
    a=x-y

    return(a)

def jkmultiplication(x,y):
    a=x*y

    return(a)

def jkdivision(x,y):
    a=x/y

    return(a)

how to call from >>> prompt

call from prompt

>>>import jksample

>>>print jkmultiplication(3,4)

12

>>>print jkaddition(100,200)

300

>>>print jkdivision(20,2)

10

>>>print jksubtraction(30,2)

28

>>>