ZBrushCentral

Loop in reverse

ZScripting Help
#1

How do you loop in reverse decrement?
And (hitting two birds with one stone) get the length of an array in Zscript?

The JavaScript equivalent of:

  s = "12345";
  o = ""
  for (var i = s.length - 1; i >= 0; i--)
  {
     o+= s[i];   
  }

>> “54321”

#2

[IButton,DoIt,
[VarSet,newStr,""]
[VarSet,whatsit,“12345”]
[VarSet,index,[StrLength,#whatsit]-1]
[Loop,[StrLength,#whatsit],
[VarSet,newStr,[StrMerge,newStr,[StrExtract,#whatsit,index,index]]]
[VarDec,index]
]
[VarSet,whatsit,newStr]
[Note,whatsit]
]

#3

Thanks for that, Marcus!

I forgot the other part - which is to loop over an array backwards appending data to a new array. I looked in the docs for arr.length (or equivalent) but could only find StrLength

Here’s that loop in JavaScript:

var arrA = [1, 2, 3, 4, 5];
var arrB = [];

for (var i = arrA.length - 1; i >= 0; i–)
{
temp = arr[i]
arrB.push(temp);
}

>> arrB = [5,4,3,2,1]

#4

In zscript you’d use a list variable. You have to define its size when it’s declared:

[VarDef,myList(10),""] // a list of ten strings

[VarDef,myList(10),0] // a list of ten floats

Then all you’d need to do is decrement the index inside the loop in the same way as above.

#5

Question: Can you have two variables (float & a string) called the same thing at the same time?
I take it you then update the array count as you modify the array?

#6

No, you can’t have two variables with the same name. But that shouldn’t matter, depending on what you’re trying to do.

You can’t change the length of a list variable dynamically, so you’d have to create it large enough for whatever you might want to put into it. You could then increment a second variable every time you added a value, so you’d know how many you’d got.

Rather than trying to directly convert javascript to zscript you’d do well to get a bit more familiar with zscript. The two languages differ quite a lot. The ZScript Command Reference gives a breakdown of what’s available.

HTH,

#7

Thanks for the help. Believe me I’ve looked over the documentation. And yes, when learning a new programming language it’s easy to fall back on another language of what you know when trying to bridge a gap of the “unknown”.

I just want to grasp a few (basic) building blocks of code - such as a for next loop in reverse, reading & writing to a file, iterating over an array, appending an array, turning a string into an int etc, before venturing out into the wild world of ZScripting.