CODEWITHSUNDEEP
javafor-loop
user472221
user472221

Reputation: 3124

using "i++" in a for loop

Hi I have a question that can I use such a this code:

        if (low != mid && mid != high) {
        for (int i = 0; i <= mid; i++) {
            boolean bool = Determinate.isPointLeftSide(a, auxiliaryListTwo.get(i), auxiliaryListTwo.get(i + 1));
            if (bool == false) {
                p = auxiliaryListTwo.get(i);

            } else {
                boolean bool1 = Determinate.isPointRightSide(a, auxiliaryListTwo.get(i + 1), auxiliaryListTwo.get(i));
                boolean bool2 = Determinate.isPointRightSide(a, auxiliaryListTwo.get(i + 1), b);
                if (bool1 == true && bool2 == true) {
                    p = auxiliaryList.get(i + 1);
                }
                else{
                    i++;
                }
            }

        }

    }

I have used "i++" in the else part ,is it correct?

Upvotes: 1

Views: 219

Answers (6)

Gordon Gustafson
Gordon Gustafson

Reputation: 41259

is it correct?

If want the code to have the effect of i = i +1, then it is correct. Since you already increment i in the for statement, i will be incremented twice if it reaches that else. As long as you have analyzed the implications of this in your code, you should be fine. In your case, you won't have to worry about out of bounds issues because the loop at the top terminates if i<=mid and there's no code after the i++. However, the loop will never be run for certain values of i when i++ is reached as it effectively skips an iteration.

Here's a quick refactoring of your code to remove useless variables. For maximum clarity, you should put the variables back but use more informative variable names, like boolean isAToTheLeftOfB = ***. Comments are your friend!!

package example;
        if (low != mid && mid != high) {
        for (int i = 0; i <= mid; i++) {
            if ( ! Determinate.isPointLeftSide(a, auxiliaryListTwo.get(i), auxiliaryListTwo.get(i + 1))) {
                p = auxiliaryListTwo.get(i);

            } else {
                if ( Determinate.isPointRightSide(a, auxiliaryListTwo.get(i + 1), auxiliaryListTwo.get(i)) && Determinate.isPointRightSide(a, auxiliaryListTwo.get(i + 1), b) ) {
                    p = auxiliaryList.get(i + 1);
                }
                else{
                    i++;
                }
            }
        }
    }

EDIT: Thanks to Vladimir for pointing out that you should use the continue statement instead of incrementing the counter directly. This is definitely more clear and less error prone.

Upvotes: 3

Fortyrunner
Fortyrunner

Reputation: 12792

Can I offer a couple of style tips?

Try not to use double negatives. E.g.

if not condition
  task for false
else 
  task for true

This can be difficult to read. It's clearer to say

if condition
  task for true
else 
  task for false

It's also not normal to say:

if (bool == false)
  do something

We normally say

if !bool
  do something

And we would not use a variable called bool but would name according to purpose. E.g.

boolean isLeftSide = Determinant....

Upvotes: 2

Vladimir Ivanov
Vladimir Ivanov

Reputation: 43108

the basic rule is that you don't change the counter variable(i here) in any way inside the loop. If you want to skip the current iteration you should use continue; statement.

Upvotes: 7

hummingBird
hummingBird

Reputation: 2555

You might want to use while loop, for things to look more logical. This is perfectly legal, but not a 'good' way to code.

Upvotes: 1

Sudantha
Sudantha

Reputation: 16224

`for (int i = 0; i <= mid; i++)

already increments if its true or false so if u use again in else it increments twice

Upvotes: 0

Vincent Ramdhanie
Vincent Ramdhanie

Reputation: 103155

Not commenting on your code particularly but it does not feel right to do that. A for loop is self managed in the sense that i is incremented for you. When you also manipulate the value of i the results are difficult to predict. Potentially you can find yourself going off the edge of a collection when you do such.

Upvotes: 1

Related Questions