Ministry of Food
Post: Network/Website Manager
Exam Date: 30-11-2022, Subject: CSE, Exam Taker: BPSC
1 (a) Name and define the components of data communication system with necessary diagram. 6 marks
Components of a Data Communication SystemA Data Communication System consists of five primary components that work together to transfer data accurately, efficiently, and securely between devices.
- Message: The message is the actual information that needs to be transmitted. It may include text, audio, video, images, or a combination of these.
- Sender: The sender is the device that originates and sends the message, such as a computer, smartphone, or other transmitting device.
- Receiver: The receiver is the destination device that receives and interprets the transmitted message.
- Transmission Medium: This is the physical path or channel through which data travels from sender to receiver. It can be wired (fiber optic, coaxial cable) or wireless (radio waves, infrared).
- Protocol: A protocol is a set of rules that governs data communication. It defines data format, transmission methods, error detection, and correction.
Data Communication System-এর উপাদানসমূহData Communication System পাঁচটি মৌলিক component নিয়ে গঠিত, যেগুলো একসাথে কাজ করে device-এর মধ্যে data সঠিকভাবে, দ্রুত এবং নিরাপদভাবে আদান-প্রদান নিশ্চিত করে।
- Message: Message হলো আসল তথ্য যা প্রেরণ করা হয়। এটি text, audio, video, image অথবা এগুলোর সমন্বয় হতে পারে।
- Sender: Sender হলো সেই device যেটি message তৈরি করে এবং পাঠায়, যেমন computer, smartphone ইত্যাদি।
- Receiver: Receiver হলো সেই device যেটি পাঠানো message গ্রহণ করে এবং বুঝতে পারে।
- Transmission Medium: Transmission medium হলো সেই পথ যার মাধ্যমে message sender থেকে receiver-এর কাছে পৌঁছায়। এটি wired (fiber optic, coaxial cable) অথবা wireless (radio wave, infrared) হতে পারে।
- Protocol: Protocol হলো নিয়মের একটি সেট যা data কীভাবে পাঠানো ও গ্রহণ করা হবে তা নির্ধারণ করে। এটি data format, error checking এবং correction নিয়ন্ত্রণ করে।
1 (b) What do you mean by transmission speed and Bandwidth? 4 marks
2 (a) Write some outstanding characteristics of E-commerce. 4 marks
2 (b) Briefly explain different payment systems used in E-commerce. 6 marks
3 (a) Can you call one constructor from another if a class has multiple constructors in Java? Briefly explain. 3 marks
3 (b) What is the difference between "compile time" and "run time" polymorphism. 2 marks
3 (c) Write a Java program to find the frequency of a character in a string. 5 marks
import java.util.Scanner;
public class CharacterFrequency {public static void main(String[] args) {
// Creating Scanner object for user input
Scanner scanner = new Scanner(System.in);
// Taking string input
System.out.print("Enter a string: ");
String str = scanner.nextLine();
// Taking character input
System.out.print("Enter the character to find frequency: ");
char ch = scanner.next().charAt(0);
// Variable to store frequency count
int count = 0;
// Loop through the string to count occurrences of the character
for (int i = 0; i < str.length(); i++)
{
if (str.charAt(i) == ch) {
count++;
}
}
// Displaying the result
System.out.println("Frequency of '" + ch + "' in the string: " + count);
// Closing scanner
scanner.close();
}
}
