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This quiz shows that the do block is executed first then the condition is evaluated. That is what happens by the do-while loop and it is different with the while-loop and the for-loop.

### Java puzzle 22: The do-while iteration

Level: Normal

What is the output of this program and why?

public class MyClass { public static void main(String[] args) { int x = 1; int y = 3; do { x++; y += 2; } while(x + y < 12); System.out.print(x + "" + y); } }

###### Author: Sar Maroof

### Answer explanation

- By do-while the do block is exectued before the evaluation of the condition. Therefore the statements x ++; and y += 2; increment the values of x and y by 1 and 2 respectively. So, x = 1 + 1 = 2. and y = 3 + 2 = 5.
- The conditoon x + y < 12 returns true, because x + y = 2 + 5. Therefore the body of the loop is executed.
- The statements x ++; and y += 2; increment the values of x and y by 1 and 2 respectively. So, x = 2 + 1 = 3; and y = 5 + 2 = 7. So, x + y = 10 and that is smaller less than 12.
- The statements x ++; and y += 2; increment the values of x and y by 1 and 2 respectively. So, x = 3 + 1 = 4; and y = 7 + 2 = 9. So, x + y = 4 + 9 = 13 and that is greater than 12. Therefore the loop is terminated.

The code writes 49 to the standard output.

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