WHILE LOOP – PRACTICE – Hi, This is Rajalakshmi!

Ex 1:

Print : 767 495 359 291 257 240 232 228

Idea:

767 495 359 291 257 240 232 228

Diff between above numbers: 272 136 68 34 17 8 4 2
- 272/2 = 136
- 136/2 = 68
- 68/2 = 34……….

public class Practice6 {

	public static void main(String[] args) {

		int a = 767;
		int b = 272;

		while (b > 1) {
			System.out.print(a + " ");
			a = a - b;
			b = b / 2;
		}

	}
}

Output:

767 495 359 291 257 240 232 228

Ex 2:

Print: 7 13 25 49 97 193 385 769

Idea:

7 13 25 49 97 193 385 769
Diff between above numbers: 6 12 24 48 96 192 384
- 6 + 6 = 12
- 12 + 12 = 24
- 24 + 24 = 48
- 48 + 48 = 96……..

public class Practice6 {

	public static void main(String[] args) {

		int a = 7;
		int b = 6;

		while (a < 800) {
			System.out.print(a + " ");
			a = a + b;
			b = b + b;
		}

	}
}

Output:

7 13 25 49 97 193 385 769

Ex 3:

Print: 7 13 25 49 85 133 193

idea:

7 13 25 49 85 133 193
Diff between above numbers: 6 12 24 36 48 60
- 6 is common number
  - 2, 4, 6, 8, 10 are multiply with 6.

public class Practice6 {

	public static void main(String[] args) {

		int a = 7;
		int b = 6;
		int c = 0;
		System.out.print(a + " ");
		while (c <= 10) {
			a = a + b;
			System.out.print(a + " ");
			c = c + 2;
			b = 6 * c;
		}
	}
}

Output:

7 13 25 49 85 133 193

Ex 4:

Print: 9 13 22 36 55 79 108

Idea:

9 13 22 36 55 79 108
- Diff between above numbers: 4 9 14 19 24 29
  - Diff Between 4 9 14 19 24 29 numbers : 5

public class Practice6 {

	public static void main(String[] args) {

		int a = 9;
		int b = 4;
		while (a <= 110) {
			System.out.print(a + " ");
			a = a + b;
			b = b + 5;
		}
	}
}

Output:

9 13 22 36 55 79 108

Ex 5:

2 4 12 48 240 1440 10080 80640 725760 7257600

Idea:

2*1 = 2

2*2 = 4

4*3 = 12

12*4 = 48

48*5 = 240

etc…….

public class Practice6 {

	public static void main(String[] args) {

		int a = 2;
		int b = 1;
		while (b <= 10) {
			a = a * b;
			System.out.print(a + " ");
			b = b + 1;
		}
	}
}

Output:

2 4 12 48 240 1440 10080 80640 725760 7257600

Ex 6:

Print: 1 2 6 15 31 56 92 141 205 286 386

Idea:

1 2 6 15 31 56 92 141 205 286 386
- Diff between numbers: 1 4 9 16 25 36 49 64 81 100
  - Diff between above numbers: 3 5 7 9 11 13 15 17 19
    - Diff between 3 5 7 9 11 13 15 17 19 numbers: 2

public class Practice6 {

	public static void main(String[] args) {

		int a = 1;
		int b = 1;
		int c = 1;
		System.out.print(a + " ");
		while (b <= 20) {
			a = a + c;
			System.out.print(a + " ");
			b = b + 2;
			c = c + b;
		}
	}
}

Output:

1 2 6 15 31 56 92 141 205 286 386

Ex 7:

Print Triangular number series: 1, 3, 6, 10, 15, 21, 28, 36, 45, 55, 66, 78, 91, 105

Idea:

1, 3, 6, 10, 15, 21, 28, 36, 45, 55, 66, 78, 91, 105
- Diff between numbers: 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14

public class Practice6 {

	public static void main(String[] args) {

		int a = 1;
		int b = 2;
		System.out.print(a + " ");
		while (b <= 14) {
			a = a + b;
			System.out.print(a + " ");
			b = b + 1;
		}
	}
}

Output:

1 3 6 10 15 21 28 36 45 55 66 78 91 105

JAVA INFINITE LOOP

A while loop can be an infinite loop if we skip writing the update statement inside its body or the condition is always true.

Syntax:

while(true condition)
{
    // while loop statements
}

BREAK STATEMENT

Break is useful when we want to stop the loop when a certain condition meets.

Ex:

public class Practice6 {
	public static void main(String[] args) {

		int num = 0;

		while (true) 
		{
			if (num == 7) 
			{
				break;
			}
			System.out.println("counting..." + num);
			num++;
		}
	}
}

Output:

counting…0
counting…1
counting…2
counting…3
counting…4
counting…5
counting…6

CONTINUE STATEMENT

Using continue, we can skip the current statement of a loop and jumps to the next statement of the loop immediately.

Ex:

public class Practice6 {
	public static void main(String[] args) {
		int num = 0;
		
		while (num < 10) 
		{
			if (num == 5) 
			{
				num++;
				continue;
			}
			System.out.println("counting..." + num);
			num++;
		}
		
	}
}

Output:

counting…0
counting…1
counting…2
counting…3
counting…4
counting…6
counting…7
counting…8
counting…9

Ex 8:

Print Odd numbers using continue

public class Practice6 {
	public static void main(String[] args) {
		int num = 0;
		
		while (num < 20) 
		{
			if (num % 2 == 0) 
			{
				num++;
				continue;
			}
		System.out.print(num + " ");
		num++;
		}
		
	}
}

Output:

1 3 5 7 9 11 13 15 17 19

Ex 9:

Print which numbers are divided by 10 (using continue statement). After 100 stop the loop.

public class Practice6 {
	public static void main(String[] args) {
		int num = 1;
		
		while (true) 
		{
			if (num % 10 != 0) 
			{
				num++;
				continue;
			}
			
			if (num > 100) 
			{
				break;
			}
		System.out.print(num + " ");
		num++;
		}
		
	}
}

Output:

10 20 30 40 50 60 70 80 90 100

Ex 10:

Print reverse number of 89532.

public class Practice6 {
	public static void main(String[] args) {
		int a = 89532;
		int b;
		
		while (a > 0) 
		{
	    b = a % 10;
		System.out.print(b + " ");
		a = a / 10;
		}
		
	}
}

Output:

2 3 5 9 8

Ex 11:

Print Reverse number of 505050
And also find addition of digits

public class Practice6 {
	public static void main(String[] args) {
		int a = 505050;
		int b;
		int sum = 0;
		
		while (a > 0) 
		{
	    b = a % 10;
		System.out.println(b + " ");
		sum = sum + b;
		a = a / 10;
		}
		System.out.println("sum of digits " + sum);
	}
}

Output:

0
5
0
5
0
5
sum of digits 15

Ex 12:

Find Sum of Digits: 978987321

public class Practice6 {
	public static void main(String[] args) {
		int a = 978987321;
		int b;
		int sum = 0;
		
		while (a > 0) 
		{
	    b = a % 10;
		sum = sum + b;
		a = a / 10;
		}
		System.out.println("sum of digits " + sum);
	}
}

Output:

sum of digits 54

Ex 13:

987654321
Decrease each digit from right to left

public class Practice6 {
	public static void main(String[] args) {
		int a = 987654321;
		int b;
		
		while (a > 0) 
		{
			System.out.println(a);
			a = a / 10;
		}

	}
}

Output:

987654321
98765432
9876543
987654
98765
9876
987
98
9

Ex 14:

Print: 2 6 8 12 14 18 20 24

Idea:

Initially 2.
Add 4 then Add 2

public class Practice6 {
	public static void main(String[] args) {
		int a = 2;
		int b;
		
		while (a <= 20) 
		{
			System.out.print(a + " ");
			b = a + 4;
			System.out.print(b + " ");
			a = b + 2;	
		}

	}
}

Output:

2 6 8 12 14 18 20 24

Ex 15:

Addition of even numbers from 0 to 20.

public class Practice6 {
	public static void main(String[] args) {
		int a = 2;
		int sum = 0;
		
		while (a <= 20) 
		{
		    sum = sum + a;
		    a = a + 2;
		}
		System.out.println("Addition of even numbers: " + sum);
	}
}

Output:

Addition of even numbers: 110

Ex 16:

Print Factorial number of 4!
factorial of 4 is 4×3×2×1, which is equal to 24

public class Practice6 {
	public static void main(String[] args) {
		int a = 4;
		int fact = 1;
		
		while (a >= 1) 
		{
		    fact = fact * a;
		    a = a - 1;
		}
		System.out.println("Factorial of number 4: " + fact);
	}
}

Output:

Factorial of number 4: 24

public class Practice1 {
    public static void main(String[] args) {
  
        int factorial = 1;
        int a = 1;
        while (a <= 4) {
  
            factorial = factorial * a;
            a++;
        }
        System.out.println("factorial is : " + factorial);
    }
}

Output:

factorial is : 24

Ex 17:

Fibonacci:

Next number is the sum of previous two numbers
The first two numbers of Fibonacci series are 0 and 1.

public class Practice1 {
    public static void main(String[] args) {
 
        int first = -1;
        int second = 1;
         
        while ((first + second) <= 55) 
        {
            System.out.print((first + second) + " ");
            second = first + second; 
            first = second - first; 
        }
    }
}

Output:

0 1 1 2 3 5 8 13 21 34 55

Ex 18:

Print each two digits from right to left: 123456

public class Practice6 {
	public static void main(String[] args) {
		int a = 123456;
		int b;
		
		while (a > 0) 
		{
			b = a % 100;
			System.out.println(b + " ");
			a = a / 100;
		}
	}
}

Output:

56
34
12

2 thoughts on “WHILE LOOP – PRACTICE”

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