Python User define Function,How to create function in python program

Python User define Function, How to create a function in the python program:-

using this we will create a set of methods to provide a proper structure to python code.

the function will subdivide the code in a single file that is easy to understand and re-use program code in the same or different file.

if we create a function-based program in python then it is called the procedural pattern of python code structure.

Syntax of function or procedure:-

def  Functionname():
     statements
     ......

Functionname()

Example of User define a function to calculate addition and subtraction in a Single File:-

def addition():     #called function

    a = int(input("enter first number"))

    b = int(input("enter second number"))

    c = a+b

    print(c)

def substraction():

    a = int(input("enter first number"))

    b = int(input("enter second number"))

    c = a-b

    print(c)

   

addition()     #calling function

substraction()

Another example of a User define a function to calculate Simple Interest using Single File:-

def calculatesi():

    p = float(input("enter value for amount"))

    r = float(input("enter value for rate"))

    t = float(input("enter value for time"))

    si = (p*r*t)/100

    print("result is ",si)

calculatesi()    

Another Example of function:-

def addition(x,y):   # parametrised fuction

    print(x+y)

def substraction():    #default function

    x= int(input("Enter First Number"))

    y= int(input("Enter Second Number"))

    z = x-y

    print(z)

addition(int(input("Enter first number")),int(input("Enter Second number")))

substraction()

substraction()

Example of Addition, Subtraction, Multiplication, and Division-based program using six different functions for input, operation, and result.

def acceptInput():

  global a,b  

  a=int(input("Enter first number"))

  b=int(input("Enter second number"))

def add():

    c=a+b

    print(c)

    def sub():

    c=a-b

    print(c)

 def multi():

    c=a*b

    print(c)

 

def division():

    c=a/b

    print(c)

def executeFunction():

    while(True):

        ch=input("Press + for addition \nfor Substraction \n * for multiplication and \n / for division")

        if ch=='+':

            acceptInput()

            add()

        elif ch=='-':

            acceptInput()

            sub()

        elif ch=='*':

            acceptInput()

            multi()

        elif ch=="/":

            acceptInput()

            division()

        else:

            break

executeFunction()

Same Program using Parametrised Function:-

 def add(a,b):

    c=a+b

    print(c)

def sub(a,b):

    c=a-b

    print(c)

def multi(a,b):

    c=a*b

    print(c)

def division(a,b):

    c=a/b

    print(c)

def executeFunction():

    while(True):

      

        ch=input("Press + for addition \nfor Substraction \n * for multiplication and \n / for division")

        if ch=='+':

            add(int(input("Num1")),int(input("Num2")))

        elif ch=='-':

            sub(int(input("Num1")),int(input("Num2")))

        elif ch=='*':

            multi(int(input("Num1")),int(input("Num2")))

        elif ch=="/":

            division(int(input("Num1")),int(input("Num2")))

        else:

            break

executeFunction()

    

Example of Addition, Subtraction, Multiplication, and Division using Two Separate files, the First file is used to write the code and the second file is used to access the code.

Save this file using Ope.py

def Add():    #Default Without Return Type

    a=100

    b=200

    c=a+b

    print(c)

def Sub():   #Default with Return Type

    a=100

    b=20

    c=a-b

    return c

def Multiplication(a,b):   #parametrised without return

    c=a*b

    print(c)

def Division(a,b):    #parametrised with return type

    c = a/b

    return c

 Create Another File to   Access the function

import Ope   # include Addition.py file here

Ope.Add()    # Addittion.py.Add()

x=Ope.Sub()

print(x)

Ope.Multiplication(100,2)

y=Ope.Division(10,2)

print(y)

Type of function:-

1)  Default or Without Parameter:- 

We can not pass input parameters in the default function, input variable will be defined under function block or globally.

1.1 With Return Type:-  

 We can return the output value from a function using the return keyword.

Syntax of Return Type Function:-

def functionname():
     statements
     return value
var = functionname()
Example of return type function in the Python program:-

def calculatesi():

    p = float(input("enter value for amount"))

    r = float(input("enter value for rate"))

    t = float(input("enter value for time"))

    si = (p*r*t)/100

    return si

res = calculatesi()

print(res)

1.2 Without Return Type:-  

We can not return value or output, output will be displayed under the function block.

Syntax of function:-

def functionname():

       statements
       print(output)

functionname()

Example of default function 

def addition():
    x=100
    y=200
    print("result is ",(x+y))

def substraction():
    x=10
    y=2
    return x-y

addition()
res = substraction()
print(res)

Assignment of default function:-

1)  WAP to reverse a five-digit number using the no return type function.

2) WAP to perform addition of complex number using return type function

3)  WAP to create a salary calculator using no return type function

4)  WAP to calculate compound interest using no return type function.

2) Parametrised:-  

The parameter is used to pass input value from calling function to called function, python provides a different type of parameters based on the requirement.

2.1)  required argument:-  

it should take all input values from calling an argument to called an argument. if we did not pass any values then it will provide an error.

def Functionname(param1,param2):
       statements

Functionname(10,20)  #code will run
Functionname(10)  #code will provide error

Example of require:-

def addition(x,y):
   print("result is ",(x+y))
addition(10)  #error
addition(10,2)

2.2) keyword-based argument:- 

using this type of function we will create a keyword for the argument which will contain the value of calling arguments to called the argument, name of the keyword argument should be the same as called argument.

Keyword means the name of the argument that will be used in the calling function.

def Functionname(x,y):

      statements

Functionname(x=10,y=20) 
Functionname(y=100,x=200)

Example of Keyword based 

def addition(x,y):
   print("result is ",(x/y))

addition(x=10,y=20)
addition(y=100,x=20)
#addition(x=10,2) #error
addition(10,2)

2.3)  default argument:-  

using this function we can set the default value to called the argument from the calling argument.

If we do not pass any value from the calling argument then the default value will be set.

def Functionname(x=10,y=20):
      Statements

Functionname(100,200)
Functionname()
Functionname(2)

Functionname(x=value1,y=value2)\

\

def addition(x=1000,y=20):

    print(x/y)

addition()    

addition(400)  

addition(400,40)

addition(x=10,y=2)

2.4)  variable length arguments:- 

We can pass multiple parameters as a tuple arguments using variable length arguments

def functionname(*args):
    Statements
    Statements
functionname(10,20,30,40,...)

We can pass a value to nth parameters as a tuple object.

Example of variable-length parameters

def addition(*x):
   for x1 in x:
     print("result is ",x1)
addition(100,4,23,34,45,5,67)

2.5) lambda function :-

It contains a single-line statement and is basically used to solve normal expressions in the program.

lambda is a keyword that is used to define the lambda function in the program.

Syntax:-

var = lambda arg1,arg2:statement

Example of lambda function in Python:-

sum = lambda x,y:x+y

print(sum(10,20))

Q) WAP to find max element using variable-length arguments?

#wap to find max element using variable length arguments

def calcMax(*x):

    m=0

    for d in x:

        if m<d:

            m=d

    else:

        print(m)

calcMax(10,23,67,89,11,45)        

Q)  How to pass dictionary object and List Object as a default function and keyword-based function in Python program?

def fun(x={'rno':0,'sname':'unknown'},m=[10,20,30]):

    print(x,m)

student= {'rno':1001,'sname':'manish kumar'}

marks = [12,45,78,89]

#fun(x=student,m=marks)  #keyword

#fun(m=marks,x=student)

#fun(student,marks)

fun()

fun(student)

fun('',marks)

fun(x=student)

fun(m=marks)

fun(x=student,m=marks)

fun(m=marks,x=student)

Q) Create a Salary Calculator using user define function?

def SalaryCal():

  name = input("Enter name")

  basic = float(input("Enter basic salary"))

  ta = float(input("Enter ta "))

  da = float(input("Enter da"))

  comm = float(input("Enter comm"))

  pf = float(input("Enter pf"))

  hra = float(input("Enter HRA"))

  lv = float(input("Enter number of leave in days"))

  ctc= basic+ta+da+comm+hra+pf

  print("CTC of employee is {0}".format(ctc))

  tsal = basic+ta+da+comm+hra

  lvded = (tsal/30)*(lv)

  gsal = tsal-lvded-pf

  print("Gross Salary is {0}".format(gsal))

  print("Leave deduction is {0} and PF deduction is {1}".format(lvded,pf))

  f = open("salaryslip.doc","a")

  f.write("\n ............................")  

  f.write("\n CTC is "+ str(12*ctc))

  f.write("\n Name is "+name)

  f.write("\n Gross Salary is {0}".format(gsal))

  f.write("\n Leave deduction is {0} and PF deduction is {1}".format(lvded,pf))

  f.write("\n ............................") 

  f.close()

Execution File:-=

import SalaryCalc

num = int(input("Enter number of employee"))

for i in range(1,num+1):

  SalaryCalc.SalaryCal()

Assignment of Parametrised function in Python:-

1) WAP to create a mark sheet program using function takes the dictionary as an input variable

2)  Create an ATM Program using a parametrized function?