introduction to computer

1. Introduction to Computer
Lab 01

2. Write a program that asks the user for their name and age, and then
prints out a greeting that includes their name and age.
public class Greeting {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
// Ask the user for their name
System.out.print("What is your name? ");
String name = scanner.nextLine();
// Ask the user for their age
System.out.print("What is your age? ");
int age = scanner.nextInt();
// Print out a greeting that includes the user's name and age
System.out.println("Hello, " + name + "! You are " + age + " years old.");
}
}

3. Write a program that takes the base and height of a triangle as
input and prints its area.
import java.util.Scanner;
public class TriangleArea {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter the base of the triangle: ");
double base = scanner.nextDouble();
System.out.print("Enter the height of the triangle: ");
double height = scanner.nextDouble();
double area = 0.5 * base * height;
System.out.println("The area of the triangle is: " + area);
}
}

4. Write a Java program that prints the first 10 even numbers
using a for loop.
public class EvenNumbers {
public static void main(String[] args) {
for (int i = 2; i <= 20; i += 2) {
System.out.print(i + " ");
}
}

5. Write a program that takes an integer as input and prints out
the first n terms of the Fibonacci sequence using a for loop.
public class Fibonacci {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter a number: ");
int n = scanner.nextInt();
int a = 0, b = 1;
for (int i = 1; i <= n; i++) {
System.out.print(a + " ");
int sum = a + b;
a = b;
b = sum;
}
}
}

6. Write a program that takes an integer as input and calculates
the factorial of that number using a for loop.
public class Factorial {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter a number: ");
int number = scanner.nextInt();
int factorial = 1;
for (int i = 1; i <= number; i++) {
factorial *= i;
}
System.out.println("The factorial of " + number + " is " + factorial);
}
}

7. Write a program that takes an integer as input and prints
whether it is even or odd.
public class EvenOrOdd {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter a number: ");
int number = scanner.nextInt();
if (number % 2 == 0) {
System.out.println(number + " is even");
} else {
System.out.println(number + " is odd");
}
}
}

8. Write a program that takes two integers as input and
determines which one is larger.
public class LargerNumber {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter the first number: ");
int number1 = scanner.nextInt();
System.out.print("Enter the second number: ");
int number2 = scanner.nextInt();
if (number1 > number2) {
System.out.println(number1 + " is larger than " + number2);
} else if (number1 < number2) {
System.out.println(number2 + " is larger than " + number1);
} else {
System.out.println("The two numbers are equal");
}
}

9. Write a program that takes an integer as input and determines
whether it is positive, negative, or zero.
public class PositiveNegative {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter a number: ");
int number = scanner.nextInt();
if (number > 0) {
System.out.println("The number is positive");
} else if (number < 0) {
System.out.println("The number is negative");
} else {
System.out.println("The number is zero");
}
}
}

10. Write a Java program that takes an integer as input and prints
the multiplication table for that number using a while loop.
public class MultiplicationTable {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
// Ask the user for the number to generate the multiplication table for
System.out.print("Enter a number: ");
int number = scanner.nextInt();
// Initialize the counter and the product
int i = 1;
int product;
// Generate the multiplication table using a while loop
while (i <= 10) {
product = number * i;
System.out.println(number + " x " + i + " = " + product);
i++;
}
}

11. Write a program that takes an input string from the user and
reverses the order of the characters.
public class StringReverse {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
// Ask the user for the input string
System.out.print("Enter a string: ");
String input = scanner.nextLine();
// Initialize an empty string to hold the reversed string
String reversed = "";
// Reverse the order of the characters in the input string
for (int i = input.length() - 1; i >= 0; i--) {
reversed += input.charAt(i);
}
// Print out the reversed string
System.out.println("The reversed string is: " + reversed);
}

12. Write a program that print 100 stars on 10 lines, 10 stars on
each line.
public class Main {
public static void main(String[] args) {
for (int i = 0; i < 10; i++) {
for (int j = 0; j < 10; j++) {
System.out.print("*");
}
System.out.println();
}
}
}

13. Write a program that finds and prints out all prime numbers
between 1 and a given number.
import java.util.Scanner;
public class PrimeNumbers {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.print("Enter a number: ");
int n = input.nextInt();
System.out.print("Prime numbers between 1 and " + n + " are: ");
for (int i = 2; i <= n; i++) {
boolean isPrime = true;
for (int j = 2; j < i; j++) {
if (i % j == 0) {
isPrime = false;
break;
}
}
if (isPrime) {
System.out.print(i + " ");