Question

Explain the different types of functions with an example.

Answer 1

Functions	Description
User-defined functions	Functions defined by the users themselves.
Built-in functions	Functions that are inbuilt within Python.
Lambda functions	Functions that are anonymous un-named functions.
Recursive functions	Functions that call themselves are known as recursive.

1. User-defined function:

Functions defined by the users themselves are called User-defined functions.

Syntax:
def :
< Block of statement >
return < expression / None>
Example:
def welcome():
print(“Welcome to Python”)
return

2. Built-in functions:

Functions which are using Python libraries are called Built-in functions.

Example:
x=20
y=-23
print(‘First number = ” ,x)
print(‘Second number = ” ,y)
Output:
First number = 20
Second number = 23

3. Lambda function:

• The Lambda function is mostly used for creating small and one-time anonymous functions.
• Lambda functions are mainly used in combination with the functions like filter]), map]) and reduce]).
  Syntax of Lambda function (Anonymous Functions):
  lambda [argument(s)]: expression

Example:
sum = lambda arg1, arg2: arg1 + arg2
print (The Sum is :’, sum(30, 40)
print (The Sum is sum(-30, 40)

Output:
The Sum is: 70
The Sum is: 10

4. Recursive function:

• A recursive function calls itself. Imagine a process would iterate indefinitely if not stopped by some condition! Such a process is known as infinite iteration.
• The condition that is applied in any recursive function is known as a base condition.
• A base condition is a must in every recursive function otherwise it will continue to execute like an infinite loop.
• Overview of how recursive function works:
• A recursive function is called by some external code.
• If the base condition is met then the. the program gives meaningful output and exits.
• Otherwise, the function does some required processing and then calls itself to continue recursion.
  Here is an example of a recursive function used to calculate factorial.

Example:
def fact(n):
if n==0:
return 1
else:
return n * fact (n-1)
print (fact (0))
print (fact (5))

Output:
1
120