Notes, summaries, assignments, exams, and problems for Computers

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THE WEB:

1. WEB1.0, WEB 2.0, WEB 3.0:

-WEB 1.0 or the read-only web: In the 1990s, information on the Internet was only for reading. It was a network of documents and people could not interact with the content. For example, they couldn’t give their opinions, ask for information or register as users. In addition, the information online was not updated very frequently. Almost everything that people used online was also part of the World Wide Web (www).

WEB 2.0 or the social network:

This was developed during the first decade of the 21st century. In this new web, information became bidirectional. Users could not only receive information, but also create and share it. New services appeared and became popular, such as email, chats, videoconferences,... Continue reading "Evolution of the Web and Information Management" »

Boston Housing Data Analysis

library(mlbench)
install.packages("dplyr")
library(dplyr)
library(ggplot2)
library(reshape2)
data("BostonHousing")
housing <- BostonHousing
str(housing)

housing %>%   ggplot(aes(x = medv)) +
  stat_density() +
  labs(x = "Median Value ($1000s)", y = "Density", title = "Density Plot of Median Value House Price in Boston") +
  theme_minimal()

summary(housing$medv)

housing %>%   select(c(crim, rm, age, rad, tax, lstat, medv)) %>%   melt( id.vars = "medv") %>%   ggplot(aes(x = value, y = medv, colour = variable)) +
  geom_point(alpha = 0.7) +
  stat_smooth(aes(colour = "black")) +
  facet_wrap(~variable, scales = "free", ncol = 2) +
  labs(x = "Variable Value", y = "Median House Price ($1000s)") +
  theme_minimal(

Vulnerabilities in Von Neumann Architecture

The system architect of the von Neumann is the way that it can allow direct memory access to the low level languages like C and C++.

If the program goes and tries to access the memory out of bound by allocating code injection to the system, it allows the system to access the memory out of the stack which causes buffer overflow and the attacker can access the other memory from the allocated stack. This way an attacker can get access to the system. Therefore von Neumann architecture is vulnerable to code injection, the effect of the buffer overflow.

Understanding Threats and Attacks

Threats

• It is a potential security violation that might exploit vulnerability of the system or assets.
• Threats can be accidental,

Transpose of a Matrix

This code demonstrates how to find the transpose of a matrix in Java.

Sorting Algorithm

This code implements a simple sorting algorithm to arrange elements in ascending order.

Complex Number Operations

This code shows how to perform operations on complex numbers in Java, such as addition.

Static Members

This code explains the concept of static members in Java and how to use them.

Function Overloading

This code demonstrates function overloading in Java, where multiple functions can have the same name but different parameters.

Derived Class and Inheritance

This code illustrates the concept of inheritance in Java, where a derived class inherits properties and methods from a base class.

Multilevel Inheritance

This code demonstrates multilevel... Continue reading "Java Programming Examples" »

C++

LET

LET'S LEARN ABOUT BASIC C++

SOURCE : GEEKS FOR GEEKS

LET'S LEARN ABOUT LOOPS

FOR LOOP

#include <iostream>

usingnamespace std;

intmain(){for(int i =1; i <=5; i++)

{ cout <<" Good morning \n";}

return0;}

WHILE LOOP

#include <iostream>

usingnamespace std;

intmain()

{int i =0;// initialization expressionwhile(i <5)

// test expression

{ cout <<"Good morning\n"; i++;// update expression}

return0;}

 DO WHILE

#include <iostream>

usingnamespace std;

intmain(){int i =2;// initialization expressiondo{ cout <<" Good morning\n"; i++;// update expression}

while(i <1);//

test expression

return0;}

SOME IMPORTANT C++ INTERVIEW QUESTIONS 

1. What are the different data types present in C++?

The 4 data types in C++ are given below:... Continue reading "Write a program in c to implement a class to represent complex members . Include member function add and multiply two complex no .Overloaded assignment operator=" »

JavaScript Cheat Sheet

JavaScript Arrays

var cars = ["Mercedes", "Tesla","Volvo"];

• pop(): Removes the last element of an array.
• push(): Adds a new element at the end of an array.
• concat(): Joins various arrays into a single array.
• reverse(): Reverses the order of elements in an array.
• indexOf(): Returns the first index of a given element in an array.
• lastIndexOf(): Returns the last index of a given element in an array.
• join(): Combines elements of an array into a single string.
• sort(): Sorts array elements based on a condition.

Global Functions

These functions are built-in to every browser that runs JavaScript:

• parseFloat(): Parses the argument and returns a floating-point number.
• parseInt(): Parses the argument and returns an integer.
• Number(): Returns a

File Management

File management is the system an operating system uses to organize and keep track of data. The operating system stores data in units called files, determines how files are stored, efficiently uses available storage space, creates a record of all file usage, and carries out every task related to files and folders.

File names typically have this structure:

filename.extension

Task and User Management

Task Management

Task management is the part of the operating system that controls the running of one or more programs on a computer simultaneously. Today's widely used operating systems support multitasking, allowing multiple tasks to run concurrently, taking turns using the computer's resources.

User Management

With user management, the operating... Continue reading "Understanding Operating Systems: File, Task, and User Management" »