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# While loop

### How while loop works?

![](/files/-LTWPtNulY9g_Gsv5LBi)

#### Syntax:

![](/files/-LTWQ1bq9v2FgvqQhNJq)

\
**Ex:**

![](/files/-LTWU-xBwxUHAzlfszFA)

#### Example 1: Program to print line 8 times

```java
// Program to print line 8 times

class Loop {
   public static void main(String[] args) {
      
      int i = 1;
	   
      while (i <= 8) {
         System.out.println("Line " + i);
         ++i;
      }
   }
}
```

When you run the program, the output will be:

```
Line 1
Line 2
Line 3
Line 4
Line 5
Line 6
Line 7
Line 8
```

Notice, `++i;` statement inside the while loop. After 8 iterations, variable i will be 9. Then, the test expression `i <= 8` is evaluated to `false` and while loop terminates.

#### Example 2: Program to find the sum of natural numbers from 1 to 100.

```java
// Program to find the sum of natural numbers from 1 to 100.

class AssignmentOperator {
   public static void main(String[] args) {
      
      int sum = 0, i = 100;
	   
      while (i != 0) {
         sum += i;     // sum = sum + i;
         --i;
      }
	   
      System.out.println("Sum = " + sum);
   }
}
```

When you run the program, the output will be:

```
Sum = 5050
```

Here, the variable sum is initialized to 0 and i is initialized to 100. In each iteration of while loop, variable sum is assigned `sum + i`, and the value of i is decreased by 1 until i is equal to 0. For better visualization,

```
1st iteration: sum = 0+100 = 100, i = 99
2nd iteration: sum = 100+99 = 199, i = 98
3rd iteration: sum = 199+98 = 297, i = 97
... .. ...
... .. ...
99th iteration: sum = 5047+2 = 5049, i = 1
100th iteration: sum = 5049+1 = 5050, i = 0
```

#### Problems:

Try all the examples as well as problems with while loop which are mentioned in [for loop](/core-java/flow-control/for-loop.md) section.