Why these two arrays are not equal, please?
Hi,
I have this JS code:
********************************************************
var tempValue = [];
function getValue (value) {
var currentValue = [];
currentValue[0] = [value, 1, 1];
if (tempValue[0] == null) {
} else {
if (currentValue[0] == tempValue[0]) {
post ("==");
} else {
post ("!=");
}
}
tempValue[0] = currentValue[0];
}
********************************************************
To the getValue function, I pass the same number multiple times (first to fill in the tempValue[0]; second to test). As the result always "!=" is posted. Why?
Thanks in advice.
This looks like the JS should log nothing the first time, and either != or == on subsequent times. I think your code is ok.
Thank you for the answer.
What is weird, if I test "if (currentValue[0] == tempValue[0])" immediately after the assignment "tempValue[0] = currentValue[0];", so the snipped looks like this:
tempValue[0] = currentValue[0];
if (currentValue[0] == tempValue[0]) {...}
then the result is true. But if I test it before (during the 2nd run), then the result is false.
If I test every single value of the arrays agains each other
((currentValue[0][0] == tempValue[0][0]) &&
(currentValue[0][1] == tempValue[0][1]) ...
then the result of all tests is also true.
I'm sorry, I was wrong. For the very first run, JS logs null. But then for every single run, it always logs "!=". I would expect "==".
Hi Martin,
I'm not 100% sure, but I think that because you store an array in the array, it is essentially an object.
So the elements stored in both currentValue[0] and tempValue[0] are JS objects, and are not the same one, so since they are not the same object, comparing them should always be false.
-N
Nikolas is correct - you're comparing Array objects, which are in separate memory spaces even if their contents are the same.
So the solution is to test all in-array elements against the same element in the 2nd array, rigt?
Would it help, if I make the currentValue also a global variable?
Yes, you have to check it element for element. It would be easier on the long run, if you haven't already, to make a .js file in the Max's "jsextensions" folder and just store your array-comparing function there (along with other of your "utilities" functions).
Just be careful if you are on a Mac, when you update/reinstall Max, the file will be deleted, so back it up!
Making it a global object won't do any difference as the comparison is still done with two objects (the two arrays).
-N