HANDS ON JAVA(OOP - based uses) (Part-I)

    Practice JAVA like Never Before!

                                                                                                    courtesy: Google Images

Day 1 🔥

Objective

Learning to code some Simple JAVA Programs:-

1. Write a program to find the sum of digits and reverse of a given integer number (take input using command-line argument).

• Program:

public class A1a{     public static void main(String args[]){         int n=Integer.parseInt(args[0]); int a, rev = 0, sum = 0;         while(n>0){             a = n % 10;             rev = rev * 10 + a; //reversing             sum = sum + a; //summing             n = n / 10;         }         System.out.println("Sum of digits:" + sum); System.out.println("Reverse:" + rev);        } }

• Output:

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2. Write a program to determine the sum of the following series for a given value of n (take input using command-line argument): 1 + 1/2 + 1/3 + ...... + 1/n. Print the result up to two decimal places.

• Program:

import java.io.*; public class A1b{     static double sum(int n){       double i, s = 0.0;       for (i=1; i<=n; i++)           s = s + 1/i;       return s;     }     public static void main(String args[]){         int n = Integer.parseInt(args[0]);         System.out.printf("Sum is %.2f", sum(n));     } }

• Output:

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3. Write a program to find the factorial of a given integer number using recursion (take input using command-line argument).

• Program:

import java.io.*; public class A1c{     public static long fact(long n){ if(n<=0) return 1; return n*fact(n-1); }     public static void main(String args[]){         long n = Long.parseLong(args[0]);         System.out.printf("Factorial is: "+fact(n));     } }

• Output:

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4. Write a program to find the real roots of the quadratic equation ax2 + bx + c = 0 where a, b and c are constants (take input using command-line argument).

• Program:

public class A1d{ public static void main(String args[]){ int a = Integer.parseInt(args[0]); int b = Integer.parseInt(args[1]); int c = Integer.parseInt(args[2]); System.out.println("The Equation is "+a+"x^2 + "+b+"x+ "+c+" =0"); int discriminant = b*b - 4*a*c; if(discriminant<0) System.out.println("No real roots"); else if(discriminant==0){ double x = -b/(2.0*a); System.out.println("Root is: "+x); } else{ double d = Math.sqrt(discriminant); double x1 = (-b+d)/(2.0*a); double x2 = (-b-d)/(2.0*a); System.out.println("The Roots are: "+x1+" and "+x2); } } }

• Output:

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5. Write a program to calculate GCD of two integer numbers (take input using command-line argument).

• Program:

public class A1e{ public static int gcd(int x, int y){ if(x%y==0) return y; return gcd(y, x%y); } public static void main(String args[]){ int a = Integer.parseInt(args[0]); int b = Integer.parseInt(args[1]); System.out.println("The GCD of "+a+" and "+b+" is: "+gcd(a, b)); } }

• Output:

<---------- End of Part - I ---------->😋