How to assign random positions to gameobjects from an array?

Here's a short example that returns a random position from a preset array of Vector3. If the position is already in use, it'll attempt to return a free one a few times, if it cannot find any, it'll return positions[0].

 var positions:Vector3[];
 var inUse:boolean[];
 var maxAttempt:int = 10;
 
 function GetPosition():Vector3
 {
     var attempt:int = 0;
     var index:int = 0;
 
     do
     {
         index = Mathf.Random.Range(0,positions.Length);
     }
     while(inUse[index] && ++attempt < maxAttempt);
 
     inUse[index] = true;
     return positions[index];
 }

Unless you want to generate the position randomly from a base position?

 function GetRandomPosition(basePosition:Vector3,radius:float):Vector3
 {
     return basePosition + Vector3(Mathf.Random.Range(-radius,radius),0,Mathf.Random.Range(-radius,radius));
 }

BY0LOG1C, Thanks so much for you answer!

I'm still wondering, how can I set the array with positions (x,y,z)?

I'm going to explain you exactly what I need, please I apologize because of my English!

When my game Load, a set of "books" (cubes) appears very near from the Camera, and after 10 seconds, each book is going to be re-located in a sideboard/shelf which is further than the books.

What I need is to create an Array that contains those positions: Example: array[0] = transform.position = Vector3(x,y,z)

And then, how can I assign to my gameobjects a random position (which are contain in the array)? Do I need a Script for each gameobject?

I'm not good at Scripting!

Thanks so much again!