Most Important Topics

Cache memory

script and interactive mode

Number Conversion

Difference between keyword and identfier

Comments in python

Membership operators

(%,// and **) Operators

Conversion of math expression into Python code(using pow(),sqrt(),exp() methods)

Mutable and immutable Data types

range() method

String slices

String Operators( +,*,membership  , relational)

Expression and statements

lvalue and rvalue

Algorithm and programs

Flow Chart , symbols  and programs

Jumping statements(break and continue)

Errors in python

Type conversion

De morgans law

Empty statement

Programs

Syntax error related questions

Output related questions

WAP to print the Reverse of given string

Find the given string in palindrome or not

Find the factorial of given number

WAP to Print the Fibonacci series

0 1   1   2   3  5   8  13  21  34

Generating triangle patterns 

WAP to find the given no is prime or not prime

Cache memory

fast speed memory used between CPU and main memory. It is used to reduce the speed mismatch of both. It increase the performance of CPU

Membership operators: 

in and not in are the membership operators in Python. They are used to test whether a value or variable is found in a sequence (string, list, tuple, set and dictionary).

x = 'Hello world'

y = {1:'a',2:'b'}

# Output: True

print('H' in x)

# Output: True

print('hello' not in x)

>1 in y

True

>'a' in y

False

>2 in y

True

>'b' in y

False

>3 in y

False

Type Conversion

Change the data type of a variable  from one type to another. There ae two type of Conversion  Explicit and Implicit

Explicit (Type Casting) :

Done by the  user  using predefined functions like int(), float(), str(), bool() etc.

a=10.5

a in float type 

if we want to convert it in integer

b=int(a)

Implicit (type promotion))

Performed by the compiler automatically  

in a mixed arithmetic expression, lower data type are automatically converted in higher type 

x = 10

>type(x)

int

y = 10.6

>type(y))

float

z = x + y

>type(z)

float

type z in automatically promoted in float

another example

a=5

type(a)

<class 'int'>

str(a)

'5'

type(a)

<class 'int'>

do nothing statement / time delay statement/ Empty  statement is pass

pass

Comments : 

Are ignore by the compiler.  

Not executed by the compiler

written using # sign or using triple quotes

#this is single line comment

""" this is 

multi line comment"""

Jumping statements(break and continue)

break: It is jumping statement. It is used to break the  for or while loop block

for example

for i in range(10):

if(i==5):

           print(i)

            break

continue: It is jumping statement. It skip current iteration and continue loop for next iteration

 example

for i in range(10):

print(i)

        if(i==5):

           continue

Output of the program will be 1 2 3 4 6 7 8 9

range()  Function

The range() function returns a sequence of numbers, starting from 0 by default, and increments by 1 (by default), and ends at a specified number.

Syntax

range(start, stop, step)

start and step is optional but stop is required. step value is by default 1 and start value is by default 0

e.g

for i in range(1,6):

  print(i)

Output 1 2 3 4 5

Statement  Output

range(3, 20, 2)   3 5 7 9 11 13 15 17 19

range(5,10)  5,6,7,8,9

range(9,3,-1)  9 8 7 6 5 4

range(10,1,-2)  10 8 6 4 2

range(5) results 0 1 2 3 4

Errors: bugs or fault in program that stop the program or produce incorrect output

Syntax Error:

Grammar mistake done by programmer.  appear at compile time, stop the execution of program.

 such as  colon mistake, indent mistake  etc. 

such as Type error, Value error, indent error, index out of range error

Logical errors

 Logical Errors occur due to  wrong program  logic. program runs but produce in correct output

avg=a+b/2

give wrong average 

correct code (a+b)/2

Runtime Errors:

 Occurs while the program is running after being successfully compiled.

Division by Zero.

Modulo Operation by Zero.

Debugging:

Debugging is the process of detecting and removing of existing and potential errors

 lvalue : object that come on the left hand side of an assignment.

 rvalue : expression that come on the right hand side of an assignment. In python everything is rvalue

a=20

b=30

c=a+b

But you cannot write as

 a+b=c 

20=a 

Algorithm

An Algorithm is a step by step procedure to solve a given problem.

Flow chart :

Pictorial  representation of an step by step solution of a problem. 

It is helpful to show the flow of execution and  explain the program

WAP to Print the Fibonacci series

0 1   1   2   3  5   8  13  21  34

a=0

b=1

print(a)

print(b)

s=a+b

for i in range(8):

    print(s)

    a=b

    b=s

    s=a+b

Given no is Prime or not Prime 

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

if(num>1):

# prime number is always greater than 1 

    for i in range(2, int(num/2)+1):

        if(num % i ==0):

            print(num, "is not a prime number")

            break

    else:

        print(num, "prime number") 

else:

    print(num, "is not a prime number")

Generating triangle patterns

(1)

1

12

123

1234

12345

s="12345"

p=""

for i in s:

    p=p+i

    print(p)

(2)

 *

**

***

****

*****

s="*****"

p=""

for i in s:

    p=p+i

    print(p)