Intro

Here, we’ll discussed about:

1. Function in Python

Self Defined vs Buitl-in functions

Declearing and Calling a function

Default Parameters

Local & Global scope of variables

2. Modules in Python

Creating a Python Module

Importing a complete module

Importing few function or constants from a module

3. Flow of Execution

4. User Input

Basics of Functions in Python

1. Functions & Their Parts

def sub1(a,b):
    print(b,"-",a,"=",b-a)

Function Name: sub1
Agruments Required: a & b (2)
Number of Statements (in body) : one (1)
Returned Value: none
Objective: it takes 2 arguments and substracts first one from the second argument

def cube2(x):
    x*x*x # a ')' at the end seems to ba a printing mistake
    return x*x*x-x

Function Name: cube2
Agruments Required: x (1)
Number of Statements (in body) : two
Returned Value: result after subtracting a number from its cube
Working: In first statement of the definition, the passed argument/number is multiplied thrice. In last statement, the same number is again multiplied thrice and then the it’s also subtracted from the resulting product i.e. cube. This final outcome is returned! Here first statement is not very significant.

def cube1(x):
    return x*x*x

Function Name: cube1
Agruments Required: x (1)
Number of Statements (in body) : one
Returned Value: cube of a number
Objective: finds the cube of a number i.e. passed as argument, by multiplying it thrice with itself

def greeting():
    print("Welcome to Python")

Function Name: greeting
Agruments Required: none
Number of Statements (in body) : 1
Returned Value: none
Objective: prints a welcome messege

2. Function Call Statements for Above (4) Definitions

## variables, to use

x,y = 3,4
num = 5

for sub1()

sub1(x,y) # (h)

4 - 3 = 1

sub1(5,3) # (k)

3 - 5 = -2

for cube1()

cube1(x) # (i)

for cube2()

cube2(num) # (l)

for greeting()

greeting() # (g)

Welcome to Python

3. Few Functions

## To return the absolute value for given number

def absolute(num):
    if num < 0:
        num *= -1
    return num

# using user defined function
print("|6|  =  ",absolute(6))  # 6
print("|-3| =  ",absolute(-3)) # 3

|6|  =   6
|-3| =   3

# using inbuilt function   abs()
print("|6|  =  ",abs(6))  # 6
print("|-3| =  ",abs(-3)) # 3

|6|  =   6
|-3| =   3

## check for even / odd number

def chkOdd(num):
    if num%2 == 0:
        print(num, "is Even")
    else:        
        print(num, "is Odd")

chkOdd(2)
chkOdd(3)

2 is Even
3 is Odd

Modules and More about the Functions

Modules in Python

Modules are just the python programs including various functions, classes and many other kinda definations.

Alone, they don’t play any majour role. But, the modules are necessary when we wish to use the functions or any other defination decleared in it. Inthis way, a python module provides a modularity.

A python module as also saved as a normal python program i.e. with the extention .py and are imported using import keyword.

the codes/modules present in current directory can be found here

Importing from same dir.

A Python Mdule to Pint a Wlcome Mssage

ASSUMING FOLLOWING BE THE MODULE hello.py, PLACED IN THE CURRENT DIRECTORY

def greet():
    print("Hey there!! Welcome to the Python Modules!")
    

# importing the module
import hello as greetings

# calling the function from module
greetings.greet()

Hey there!! Welcome to the Python Modules!

Importing from external/another dir.

import sys
sys.path.append('../dependancies/modules/')

import welcome
welcome.greeting()

Hey there!! Welcome to the Python Modules!

welcome.name = welcome.setName()
welcome.msg(welcome.name)

Hello World!!

welcome.name = welcome.setName("Ravi")
welcome.msg(welcome.name)

Hello Ravi!!

This module can be found here

Exercise

1. Module to find sum & product

import basicMath as m

print("2 + 3 = ",m.sum(2,3))

2 + 3 =  5

print("2 X 3 = ",m.product(2,3))

2 X 3 =  6

2. Python function to identify a leap year

def isLeap(year):
    flag = False
    if year%100 == 0 and year%400 == 0:
        flag = True
    elif year%100 != 0 and year%4 == 0:
        flag = True

    return flag

if(isLeap(2020)):
    print("2020 is a leap year!")
else:
    print("2020 is NOT a leap year!")

2020 is a leap year!

## True = Leap year  |   False = NOT Leap year

print(isLeap(1992))
print(isLeap(2000))
print(isLeap(1900))
print(isLeap(2100))

True
True
False
False

3. Local VS Global variables in python

# if there is only a Global variable with a name, 
    # it's value is used everywhere in the module/program

name = "Myname"

def caller():
    print("Hey",name, "!!")
    
caller()

Hey Myname !!

# if there is only a Local variable with a name, 
    # it's value is used everywhere wuthin that particular function / class

def caller():
    name = "Myname"
    print("Hey",name, "!!")
    
caller()

Hey Myname !!

# if there are 2 or more variable with same name, (including Global and Local(s), both)
    # keyword 'global' is used to call the global variable

name = "Myname"

def caller():
    global name
    name = "My name"  # this would change the global variable's value
    print(name," is not 'Myname'!!")
  
caller()
print(name)

My name  is not 'Myname'!!
My name

4. Module to find pow(x,n)

import power

power.pow(2, 10)

5. Create roll_D(noOfSides, noOfDice) and generate random roll values

# since default arguments can only come after defaults, 
# making both the arguments default in order to maintain the order

import random as rand

def roll_D(noOfSides = 6, noOfDice = 1):
    roll = 1
    while roll <= noOfDice:
        outcome = rand.randint(1,noOfSides)
        print(outcome)
        roll += 1
    print("That's all")

Checking for given condition i.e. (6,3)

roll_D(6,3) # 3 dice with 6 faces, each

2
4
4
That's all

Some othe examples

roll_D() # one die with 6 faces

6
That's all

roll_D(8) # one die with 8 faces

1
That's all

roll_D(noOfDice = 2) # 2 dice with 6 faces, each

3
5
That's all

roll_D(7,3) # 3 dice with 7 faces, each

6
4
2
That's all

6. Prime / Non-Prime Function

def isPrime(num):
    if num == 2 or num == 3:
        flag = True
    elif num%2 != 0:
        for i in range(3, int(num/2)):
            if num%i != 0:
                flag = True
                continue
            else:
                flag = False
                break
    else:
        flag = False
        
    return flag

num = 8

if(isPrime(num)):
    print(num,"is Prime")
else:
    print(num,"is NOT Prime")

8 is NOT Prime

num = 13

if(isPrime(num)):
    print(num,"is Prime")
else:
    print(num,"is NOT Prime")

13 is Prime

Sum of square of first and last 2 digits

def void(num):
    if num not in range(1000,9999):
        return -1
    else:
        first = int(num/100)
        last = num%100
        return first**2 + last**2
        

num = 235

res = void(num)
if res == -1:
    print("Invalid input!!")
else:
    print("Calculated result: ",res)

Invalid input!!

num = 2315

res = void(num)
if res == -1:
    print("Invalid input!!")
else:
    print("Calculated result: ",res)

Calculated result:  754

Check for Vowel

def isVowel(char):
    vowels = ['a','e','i','o','u','A','E','I','O','U']
    flag = False
    
    if char in vowels:
        flag = True
    
    return flag

# prints True if passed charector is a Vowel
print(isVowel('u'))
print(isVowel('k'))
print(isVowel('m'))
print(isVowel('i'))

True
False
False
True

Mersenne Number

# declearing fun.
def mersenne(num):
    return 2**num - 1

# input the value for number
n = input("Enter the number: ")

Enter the number: 5

# the result
print("Mersenne number is: ",mersenne(int(n)))

Mersene number is:  31

Computer-Science-with-Python

It's a repository made to cover the programming syllabus of class 12th (CBSE) in Python.