Ways to evaluate loops

[James Chegwidden]

The following code will output Hi six times

 
i = 5;
while (i <= 10)
{
  System.out.println("Hi');
  i++;
}
 

What is the quick formula(s) way for evaluating no. of times a loop will be processed without actually evaluating the loop? Example for above

is it 10-5 + 1= 6



If you actually trace through the code you will see Hi is printed six times.

I thought there was a quick way to do this?
Just like to show my classes different ways to evaluate loops

[Kalai Selvan]

Hi James,
The formula will look some thing like this

(Final - Initial) / Step

Where Final is the final value.
Initial is the initial value and
Step is the increment value.

for <= condition we have to increment Final by one.

In idle condition (i.e. without any conditional break or jump etc.)the loop will execute these many times.

Regards,
Kalai Selvan T.

[James Chegwidden]

Formula not quite right:

 
public class TestLoop
{
 
public static void main(String[] args)
 {
   int count = 1;
   int num = 25;
   while (count < 25)
   {
     num = num - 1;
     count++;
   }
   System.out.println(count+ " "+ num);
 }
}

prints 25 and 1

Formula given above (25- 1)/1 =24 times which is not correct.

So formula does not work for all cases.

[Francis Siu]

What is the quick formula(s) way for evaluating no. of times a loop will be processed without actually evaluating the loop?
I suggest you to read some books which contain the algorithm analysis.
From your example, I know that it is required 0(n) which n representing the times of the for loop.
Hope this help

[Hosh Nasi]

I may be way off here but wouldn't (x+1)-y = z work? This of course would only work if the ending value is greater then the starting value, and it is a >= statement. Is this just an general thought? Or are you looking for code for this too?