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# Fruitful Function - Python

Fruitful function · Void function · Return values · Parameters · Local and global scope · Function composition · Recursion

Fruitful Function

·                 Fruitful function

·                 Void function

·                 Return values

·                 Parameters

·                 Local and global scope

·                 Function composition

·                 Recursion

## Fruitful function:

A function that returns a value is called fruitful function.

Root=sqrt(25)

a=10

b=20

c=a+b

return c

print(c)

## Void Function

A function that perform action but don’t return any value.

print(“Hello”)

a=10

b=20

c=a+b

print(c)

## Return values:

return keywords are used to return the values from the function.

example:

return a – return 1 variable

return a,b– return 2 variables

return a,b,c– return 3 variables

return a+b– return expression

return 8– return value

## PARAMETERS / ARGUMENTS:

v       Parameters are the variables which used in the function definition. Parameters are inputs to functions. Parameter receives the input from the function call.

v       It is possible to define more than one parameter in the function definition.

## Types of parameters/Arguments:

1.              Required/Positional parameters

2.              Keyword parameters

3.              Default parameters

4.              Variable length parameters

## Required/ Positional Parameter:

The number of parameter in the function definition should match exactly with number of arguments in the function call.

### Example

def student( name, roll ):

print(name,roll)

student(“George”,98)

George 98

## Keyword parameter:

When we call a function with some values, these values get assigned to the parameter according to their position. When we call functions in keyword parameter, the order of the arguments can be changed.

### Example

def student(name,roll,mark):

print(name,roll,mark)

student(90,102,"bala")

90 102 bala

## Default parameter:

Python allows function parameter to have default values; if the function is called without the argument, the argument gets its default value in function definition.

### Example

def student( name, age=17):

print (name, age)

student( “kumar”):

student( “ajay”):

Kumar 17

Ajay 17

## Variable length parameter

v       Sometimes, we do not know in advance the number of arguments that will be passed into a function.

v       Python allows us to handle this kind of situation through function calls with number of arguments.

v       In the function definition we use an asterisk (*) before the parameter name to denote this is variable length of parameter.

### Example

def student( name,*mark):

print(name,mark)

student (“bala”,102,90)

bala ( 102 ,90)

## Local and Global Scope

### Global Scope

v       The scope of a variable refers to the places that you can see or access a variable.

v       A variable with global scope can be used anywhere in the program.

v       It can be created by defining a variable outside the function. Local Scope A variable with local scope can be used only within the function . ## Function Composition:

v       Function Composition is the ability to call one function from within another function

v       It is a way of combining functions such that the result of each function is passed as the argument of the next function.

v       In other words the output of one function is given as the input of another function is known as function composition.

### Example:

math.sqrt(math.log(10))

c=a+b

return c

def mul(c,d):

e=c*d

return e

e=mul(c,30)

print(e)

900

### find sum and average using function composition

def sum(a,b):

sum=a+b

return sum

def avg(sum):

avg=sum/2

return avg

a=eval(input("enter a:"))

b=eval(input("enter b:"))

sum=sum(a,b)

avg=avg(sum)

print("the avg is",avg)

output

enter a:4

enter b:8

the avg is 6.0

## Recursion

A function calling itself till it reaches the base value - stop point of function call. Example: factorial of a given number using recursion

Factorial of n

def fact(n):

if(n==1):

return 1

else:

return n*fact(n-1)

n=eval(input("enter  no. to  find

fact:"))

fact=fact(n)

print("Fact is",fact)

### Output

enter no. to find fact:5

Fact is 120

### Explanation ### Examples:

1.              sum of n numbers using recursion

2.              exponential of a number using recursion

### Sum of n numbers

def sum(n):

if(n==1):

return 1

else:

return n*sum(n-1)

n=eval(input("enter  no. to  find

sum:"))

sum=sum(n)

print("Fact is",sum)

### Output

enter no. to find sum:10

Fact is 55

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