User Defined Functions

M3-R5.1 · Chapter 6: Functions · 5 min read

User Defined Functions: The functions those are defined by the user are called user defined functions and These functions are created by using the  

The syntax to define a function is:

Function Body: Statements that define what the function does. And the body can contain one or more   statements

   Return value :  Optional                          Parameter:  Optional

              Q: Every function must have a return value->      Ans : -> False

Point to remember…………….

  • Keyword def marks the beginning(start) of the functions header
  • Function Name to uniquely identify it. And must follow the naming rules same as for identifiers
  • Functions may or may not contain arguments.
  • A colon(: )  to marks the end of function header
  • Functions can take one or more statements to perform a specific task. And statements must have same indentation level
  • An optional return statement to return a value from the function.
  • Function must be called /invoked to execute its code.
  • All statements within the same block must have same indentation
  • Parameters (arguments) through which we pass values to a function. They are optional.

Calling the function:

  • Once we have defined a function, we can call it from another function, program or even the Python prompt. To call a function we simply type the function name with appropriate parameters.

            Syntax:    function-name(parameter)    # parameter is optional

            Example:    Add (10,20)       #here 10 and 20 is a parameter for add () function

The return statement:  The return statement is used to exit a function and go back to the place from where it was called.

                 There are two types of functions according to return statement:

a. Function returning some value (non-void function)

b. Function not returning any value (void function)

Example:

def Display():

       print(“Never Give Up !!!”)

Display()

def Display():

            print(“Good Morning…..”)

           print(“***************”)

Display()

def Display1():

        print("Good Morning…..")

        print("***************")

def Display2():

        print("Good Afternoon…..")

        print("###############")

def Display3():

        print("Good Evening…..")

        print("-------------------")

Display1()

Display2()

Display3()

Q: Write a program to add two number using function

def Add():

    num1=int(input("Enter First Number:"))

    num2=int(input("Enter Second Number"))

    sum=num1+num2

    print("Addition =",sum)

Add()

OUTPUT: Enter First Number: 14

                  Enter Second Number: 25

                  Addition=39

Q: Write a program to calculate sinple Interest using function

def simple_interest():

    p=int(input('Enter The principal:'))

    t=int(input('Enter The time:'))

    r=int(input('Enter The rate:'))

    si = (p * t * r)/100

    print('The Simple Interest is', si)

simple_interest()

def simple_interest(p,t,r):

    print('The principal is', p)

    print('The time period is', t)

    print('The rate of interest is',r)

    si = (p * t * r)/100

    print('The Simple Interest is', si)

simple_interest(1000, 2, 3)

def simple_interest(p,t,r):

    print('The principal is', p)

    print('The time period is', t)

    print('The rate of interest is',r)

     si = (p * t * r)/100

     print('The Simple Interest is', si)

P = int(input("Enter the principal amount :"))

T = int(input("Enter the time period :"))

R = int(input("Enter the rate of interest :"))

simple_interest(P,T,R)

Q: Write a program to check odd or even number using function

def odd():

    num = int(input("Enter a number: "))

    if (num % 2) == 0:

           print("{0} is Even number".format(num))

    else:

           print("{0} is Odd number".format(num))

odd()

Q: Write a program to print the factorial of a  number using function

def fact():

   num = int(input("Enter a number: "))

   factorial = 1

   if num < 0:

       print(" Factorial does not exist for -ve numbers")

   elif num == 0:

       print("The factorial of 0 is 1")

   else:

       for i in range(1,num + 1):

           factorial = factorial*i

   print("The factorial of",num,"is",factorial)

fact()

#Python program to print the power of 1st number to the 2nd number using function

def power(x, n):

     result = 1

     for i in range(n):

          result=result*x

     return result

a = int(input("Enter number "))

b = int(input("Raise to power "))

pw = power(a, b)

print(a, "raise to power", b, "is", pw)