gameObject[] Length

How can i set the length of a gameObject in the Start function???

Here is an excellent link that you should keep permanently bookmarked !

The type of array you are suggesting here is a Built In array, so scroll down to (Im assuming uJS here) :

 var myNumbers = new int[10];                   // declaration example using ints

Quick tip : only use a Built In array for something that is going to be of fixed size , meaning the length of the Built In array is never going to change.

For an array that you add too and take away from, use Generic List, keep scrolling down that page and all the notes on how to use it are there. Here is a checksheet I made from this page (again in uJS) :

My list notes :

// to use List
import System.Collections.Generic;

// declare
var inRangeList : List.< GameObject > = new List.< GameObject >();

var inRangeList : List.< GameObject >;
inRangeList = new List.< GameObject >();

// Add object to list :  
inRangeList.Add( theItem );

// length

// from position 
inRangeList[ index ];

// empty list

// send to builtin array