while loop exceeding specified condition?

Question

Program that calculates and shows the value of (2 to the 10th power)

This statement results in 1024. I'm not understanding how it keeps looping after it reaches "9". Does "< 10" mean loop around ten times, or loop up to a sum less than "10"? Would appreciate someone explaining this to me. Thanks!

var result = 1;
var counter = 0;
while (counter < 10) {
  result = result * 2;
  counter = counter + 1;
}
show(result);

Answer 1

Your counter is running ten times, once each for the values 0-9. When writing loops like that (that include a < ) I think of the 10 as "this loop will be running ten times." It's helped a lot with minor issues like this.

Remember, there are only two really hard things in programming: cache validation, variable substitution, and off-by-one errors.

Answer 2

loop 1: result = 1*2 (2) counter = 1
loop 2: result = 2*2 (4) counter = 2
loop 3: result = 4*2 (8) counter = 3
...
loop 10: result = 512*2 (1024)counter = 10

Answer 3

It loops 10 times and as such it multiplies by two ten times and as such gives you 2^10 = 1024. Exactly. PS If you only want this multiplication, you'd be better off with

result = 1 << 10

Answer 4

Yes ten times 0 to 9 = 10.

When the compiler sees if 10 < 10 it evaluates to false. If you want to see 10 change the condition to <=

Answer 5

The program will only step inside the loop if the condition for the while-loop is met. So you check it before entering the loop.

If you want the program to step inside the loop one more time, either use a do-while loop where you check the condition after the execution of the loop. You can also change the condition to "counter <= 10" and use the while-loop as is.

Here you can find more information on while-/do-while-loops and also breaks in javascript.

Answer 6

When counter is 1 it result is 2^1 When counter is 2 it result is 2^2

Since counter is 10 at the end of the loop, result is 2^10 .