python

  User Defined Exception in Python  Theory In Python, an exception is an error that occurs during program execution and interrupts the normal flow of the program. Sometimes the built-in exceptions are not enough for a program. In such cases, programmers can create their own exceptions called User Defined Exceptions . A user defined exception is created by defining a new class that inherits from the Exception class . This helps programmers handle custom errors based on specific conditions in the program . Syntax class ExceptionName ( Exception ): pass Basic Example Program # User Defined Exception Example class AgeError ( Exception ): pass age = int ( input ( "Enter your age: " )) try : if age < 18 : raise AgeError else : print ( "You are eligible to vote" ) except AgeError : print ( "Error: Age must be 18 or above" ) Sample Output Case 1 Enter your age: 20 You are eligible to vote Case 2 En...

  Database Operations in Python Creating Tables, Insert, Update, Delete, Read and Transaction Control Python can interact with databases using modules like sqlite3 . It allows programmers to perform database operations such as creating tables, inserting records, updating data, deleting data, and reading records . These operations are commonly called CRUD operations : Create – Create tables and insert data Read – Retrieve data from tables Update – Modify existing records Delete – Remove records from tables Python also supports Transaction Control , which ensures database operations are completed safely. 1. Creating a Table A table is created using the CREATE TABLE SQL command. import sqlite3 conn = sqlite3 . connect( "college.db" ) cursor = conn . cursor() cursor . execute( """ CREATE TABLE IF NOT EXISTS student( id INTEGER PRIMARY KEY, name TEXT, department TEXT ) """ ) conn . commit() 2. Insert Data ...

  Date and Time Module in Python  Python provides built-in modules to work with date and time . The most commonly used modules are: datetime module – used to work with dates and times. time module – used for time-related functions such as delays and timestamps. 1. datetime Module The datetime module helps to get the current date, time, and perform date calculations . Importing the module import datetime Example: Display Current Date and Time import datetime now = datetime . datetime . now() print ( "Current Date and Time:" , now ) Output (example): Current Date and Time: 2026-03-09 10:30:15.234567 Example: Display Only Current Date from datetime import date today = date . today() print ( "Today's Date:" , today ) Output: Today's Date: 2026-03-09 Example: Formatting Date and Time from datetime import datetime now = datetime . now() formatted = now . strftime( "%d-%m-%Y %H:%M:%S" ) print ( "Formatt...

  Built-in Modules in Python  Built-in modules are modules that come pre-installed with Python . You do not need to install them separately . They provide ready-made functions and classes to perform common tasks such as mathematics, date handling, file operations, and system interaction. You can use them in a program using the import statement. import module_name Example: import math print ( math . sqrt( 25 )) Output: 5.0 Common Built-in Modules in Python 1. math Module  Provides mathematical functions. Example: import math print ( math . sqrt( 16 )) print ( math . factorial( 5 )) print ( math . pi) Functions: sqrt() – Square root factorial() – Factorial value pi – Value of π pow() – Power calculation 2. random Module  Used to generate random numbers. Example: import random print ( random . randint( 1 , 10 )) print ( random . choice([ 10 , 20 , 30 , 40 ])) Functions: randint() – Random integer choice() – Random se...

  Decision Making in Python (with Diagram)  In Python , decision making allows a program to choose different actions based on conditions . The program evaluates a condition and decides which block of code should execute. Decision making is done using conditional statements like if , if-else , and if-elif-else . if Statement The if statement executes a block of code only when the condition is True . Syntax if condition : statement Example x = 10 if x > 5 : print ( "x is greater than 5" ) Diagram (Flowchart) Start | Condition | +----+----+ | | True False | | Execute Skip Statement Statement | End if – else Statement The if-else statement is used when there are two possible outcomes . Example num = 7 if num % 2 == 0 : print ( "Even Number" ) else : print ( "Odd Number" ) Diagram Start | Check ...

  Types of Loops in Python  In Python , loops are fundamental control structures that allow a program to execute a block of code repeatedly . They are commonly used for tasks like processing lists, iterating through data, or performing repeated calculations. Python mainly provides two primary types of loops . 1. For Loop The for loop is used to iterate over a sequence such as a list, tuple, string, or a range of numbers. It is typically used when the number of iterations is known . Syntax for variable in sequence : # code block Example for i in range ( 5 ): print ( i ) Output 0 1 2 3 4 Explanation range(5) generates numbers from 0 to 4 . The loop runs once for each value in the sequence. 2. While Loop The while loop repeatedly executes a block of code as long as a condition remains true . It is commonly used when the number of iterations is not predetermined . Syntax while condition : # code block Example i = 1 while i <=...

  Types of Operators in Python  In Python , operators are special symbols used to perform operations on variables and values . They are an essential part of programming because they allow calculations, comparisons, and logical decisions. Python provides several types of operators.  Arithmetic Operators These operators perform mathematical calculations . Operator Meaning Example + Addition 5 + 3 = 8 - Subtraction 5 - 3 = 2 * Multiplication 5 * 3 = 15 / Division 6 / 3 = 2.0 % Modulus (remainder) 5 % 2 = 1 ** Exponent (power) 2 ** 3 = 8 // Floor division 7 // 2 = 3 Example a = 10 b = 3 print ( a + b ) print ( a % b )  Comparison (Relational) Operators These operators compare two values and return True or False . Operator Meaning Example == Equal to 5 == 5 != Not equal 5 != 3 > Greater than 7 > 5 < Less than 3 < 5 >= Greater than or equal 5 >= 5 <= Less than or equal 3 <= 4 Example x = 5 y = 10 print ( x < y ) ...