31. Program to check if number is prime or not:
package sam2;
import java.util.Scanner;
public class Prime {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner scn = new Scanner(System.in);
//Asking for Input
System.out.println("Enter the number you want to check : ");
int number = scn.nextInt();
if (number == 2) {
System.out.println("2 is a Prime Number !!!");
}
else {
int count = 0;
//logic
for (int div = 2; div * div <= number ; div++) {
if (number % div == 0) {
count++;
}
}
if (count == 0) {
System.out.println(""+number+" is a Prime Number !!!");
} else {
System.out.println(""+number+" is NOT a Prime Number !!!");
}
}
}
}
32. Program to print reverse of a number.
package sam2;
import java.util.Scanner;
/*
* Java Program To Reverse a Number
*/
public class Reverse {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner sc = new Scanner(System.in);
System.out.println("Enter value of n: ");
int num = sc.nextInt();
int originalNumber = num;
int reversedNumber = 0;
while(num > 0){
int digit = num % 10;
num = num / 10;
reversedNumber = reversedNumber * 10 + digit;
}
System.out.println("Original Number : "+originalNumber);
System.out.println("Reversed Number : "+reversedNumber);
}
}
33. Program to swap two number.
package sam2;
import java.util.Scanner;
public class SwapNumber {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner sc = new Scanner(System.in);
System.out.println("Enter first number: ");
int firstNum = sc.nextInt();
System.out.println("Enter second number: ");
int secondNum = sc.nextInt();
//Before Swapping two numbers
System.out.println("Before Swapping :");
System.out.println("First number is "+firstNum);
System.out.println("Second number is "+secondNum);
//Swapping the numbers
int temp = firstNum;
firstNum = secondNum;
secondNum = temp;
//After Swapping two numbers-
System.out.println("After Swapping :");
System.out.println("First number is "+firstNum);
System.out.println("Second number is "+secondNum);
}
}
33. Program to add two numbers using function.
package sam2;
/*
* Java Program to Add Two Numbers Using Functions
* By Rahul Kundu
*/
import java.util.Scanner;
public class SumFunction {
public static int sum(int n1, int n2) {
int ans = n1 + n2;
return ans;
}
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner sc = new Scanner(System.in);
System.out.println("Enter the first number: ");
int n1 = sc.nextInt();
System.out.println("Enter the second number: ");
int n2 = sc.nextInt();
int sum = sum(n1,n2);
System.out.println("The sum of "+n1+" and "+n2+" is "+sum);
}
}
34. Program to find sum of array:
package sam2;
public class SumArray {
public static void main(String[] args) {
// TODO Auto-generated method stub
int arr[] = new int[] {1, 3, 4, 6, 7, 8};
int sum = 0;
for (int i = 0; i<arr.length;i++) {
sum = sum + arr[i];
}
System.out.println("Sum of all the elements of an array: " + sum);
}
}
35. Program to find Reverse of String.
package sam2;
import java.util.Scanner;
public class StringRev01 {
public static void main(String[] args)throws java.lang.Exception
{
Scanner sc = new Scanner(System.in);
System.out.println("Enter a word: ");
String str = sc.nextLine();
// Convert String to character array
char ch[]=str.toCharArray();
// Reversing the String
String rev="";
for(int i=ch.length-1;i>=0;i--){
rev+=ch[i];
}
System.out.println("Reverse of "+str+ " is " +rev);
}
}