How to find even numbers in cp[i]?

Forum|Forum|8 months ago
July 28, 2025
1 reply
194 views

var cp = pp.marginPreferences.columnsPositions;

I now want to distinguish between odd and even numbers.
cp[1], cp[3], cp[5]
cp[2], cp[4], cp[6]
I previously used cp[2*i] to represent even numbers and cp[2*i-1] to represent odd numbers, but in practice, as the numbers grow larger, the logic becomes confusing.
For example, when i=11, 2*i becomes 22, which is no longer near 11.

I think the correct logic should be:
Odd number + 1 = Even number.

Scripting

Correct answer m1b

@dublove you would use remainder operator (%). Something like this:

var doc = app.activeDocument;
var cp = doc.pages[0].marginPreferences.columnsPositions;
var even = [];
var odd = [];

for (var i = 0; i < cp.length; i++) {
    if (0 === i % 2)
        even.push(cp[i]);
    else 
        odd.push(cp[i]);
}

- Mark

m1b

Correct answer

Community Expert

@dublove you would use remainder operator (%). Something like this:

var doc = app.activeDocument;
var cp = doc.pages[0].marginPreferences.columnsPositions;
var even = [];
var odd = [];

for (var i = 0; i < cp.length; i++) {
    if (0 === i % 2)
        even.push(cp[i]);
    else 
        odd.push(cp[i]);
}

- Mark

dubloveAuthor

Legend

Hi m1b,

It should be even.push(i);

I thought it could be done directly like this:
ev=even(i);

I understand now, thank you very much.

m1b

Community Expert

Yes `even` and `odd` in my example are Arrays, and push is a method to add something to the end of the array. So my example will put items 0,2,4,6,8 etc into even and items 1,3,5,7,9 etc into odd. Rememer that the first index of an array is 0, not 1.

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