Python function

In this post we will cover function in Python. You can watch our videos on function in Python – Click Here

Q.1 What is function?
Ans.

• A function is a block of reusable code that runs only when it is called
• You can pass data, known as parameters, into a function
• A function can return data
• Example:

def square(n):    #square is function 
     return (n*n)
print ("The square of 3 is ")
print (square(3))      # call the function

Q.2 Why do we need function?
Ans.

• Functions provide better modularity for your application
• It provide a high degree of code reusing
• The same function can be called multiple times by your code

Q. 3 What are different types of Python Functions?
Ans. Python functions can belong to one of the following three categories

1. Built-in functions -These are pre-defined functions and are always available for e.g. len( ), type( ), int( ), input( ) etc.
2. Functions defined in modules-These functions are pre-defined in particular modules and can only be used when the corresponding module is
   e.g.sin()
3. User defined Functions– Programmer can create their own

Q.4 How do you define function in Python?
Ans.

• Function blocks begin with the keyword def followed by the function name and parentheses ( ( ) ).
• Any input parameters or arguments are placed within these
• We can add multiple arguments separated by a
• The function definition ends with colon (:)
• The body of the function is The function block ends where the indentation ends like for if and for statements.
• The statement return exits a function, optionally passing back data to the
• A return statement with no arguments is the same as return
• If there’s no return statement, then function is called void
• To call a function, use the function name followed by
  Syntax:

def functionname( parameters ):
  "function_docstring"
   function_suite
   return [expression]

Q.5 What are Positional Arguments?
Ans. When the function call statement must match the number and order of arguments as defined in the function definition, this is called the positional argument matching

def power(n,r):
 return (n**r)
print ("The 2 raise to power 3 is ", power(2,3))# call the function

Q. 6 What are Default Arguments? Give its advantages.
Ans. A parameter having a default value in function header is known as a default parameter. It becomes optional in function call.
Function call may or may not have value for it

Advantages

• They can be used to add new parameters to the existing functions
• They can be used to combine similar functions into one

Example

def power(n, r=2): 
     return (n**r)
print ("2 raise to power 2 is ", power(2)) # call the function

Q. 7 What are Keyword (Named) Arguments?
Ans. Keyword arguments are the named arguments with assigned values being passed in the function call statement

def power(n,r):    
     return (n**r)
print ("The 2 raise to power 3 is", power(r=3, n=2))      # call the function

Q.8 What is the difference between void and non-void functions?
Ans.

Q.9 What is the difference between formal and actual parameters?
Ans.

• Actual Parameters: The values passed are called Actual Parameters,

• Formal Parameters: The values received in the function definition header is called Formal parameters
  e.g.

        def power(n,r):    # n and r are formal parameters 
              return (n**r)
        power(10,2)     # 10 and 2 are actual parameters

Q.10 Difference between Global Scope and Local Scope.

Ans.

Q. 11 What is the difference between call by value and call by reference
Ans.

Q. 12 What is global keyword?
Ans. When we want a variable which is local to be available globally, we declare it with global keyword before it is used.
e.g.

def func(b):
     global c
     c = a + b
     return c
print (func(4) )# gives 4+5=9
print (c) # now c is defined (9)

Q. 13 Write the syntax of lambda functions.
Ans. The syntax of lambda functions contains only a single statement which is as follows: Lambda[arg1,[arg2…..argn]]: expression

Q. 14 What is the use of lambda keyword in Python?
Ans. You can use the lambda keyword to create small anonymous functions

Q. 15 Differentiate between Built-in functions and functions defined in modules.
Ans.

Q. 16 How are following two statements different import math and from math import?
Ans.

Q. 17 What are Default arguments?
Ans.

• Value of some arguments are specified in the parameters of the function
• Such arguments are called default
• These values are used in case no matching argument is passed in the function calls

Q. 18 What is a default parameter? How is it specified?
Ans.

• A parameter having default value in the function header is known as a default
• A parameter van be specified as default only if all the parameters on its right are specified as
• Syntax : def(arg1,arg2—arg x=):
        arg x will now be a default parameter with default value as the value specified

Q. 19 Explain anonymous functions.
Ans.

• You can use lambda keyword to create small anonymous functions.
• These functions are called anonymous because they are not declared in the standard manner by using the def keyword, lambda functions have their own local namespace and cannot access variables other than those in their parameter list and those in the global namespace

Q. 20 What is _main_?
Ans. The segment with top level statements is named as _main_ by Python

Q. 21 What is _name_?
Ans. It is built in variable that states the name of the top level statements i.e. _main_

Q. 22 How are docstring different from comments
Ans.

• Docstrings are different from comments because docstrings are stored as documentation of the corresponding module or function or class and can be displayed using help() function with name of the corresponding module/function/class as parameter
• e. g. help(math), help(math.pow) etc. This is not true with comments

Q. 23 Write a python function to reverse the string.
Ans.

def
   reverse_string(str): 
   str1 = ""
   for i in str:
      str1 = i + str1
   return str1 # return the reverse string
str = "SimplyCoding" # input String 
print("The original string is: ",str)
print("The reverse string is",reverse_string(str)) # Function call

Q. 24 Write a python function to find factorial of given number
Ans.

def factorial(n):
  if n < 0:
    return 0
  elif n == 0 or n == 1: 
    return 1
  else:
    fact = 1
    while(n > 1):
      fact *= n 
      n -= 1
      return fact
num = 5;
print("Factorial of",num,"is", factorial(num))

Q. 25 Write a function to calculate simple interest and default value for time is 1 year and rate is 7%.
Ans.

def cal(p,r=7, t=1)
  l= (p*r*t)/100
  return l
print(cal(4000)) 
print(cal(4000,10)) 
print(cal(4000,10,5))

Q. 26 Write a function called show_stars(rows). If rows is 5, it should print the following:

*
**
***
****
*****

Ans.

def show_stars(rows):
 for i in range(0,rows):
   for j in range(0,i+1): 
     print(“*”,end = “”)
   print(“\n”)
print(show_stars(5))

Q. 27 Write output of the following Python code?

x = 50
def func():
  global x 
  print('x is', x) 
  x = 2
  print('Changed global x to', x) 
func()
print('Value of x is', x)

Ans.

x is 50
Changed global x to 2
Value of x is 50