How to check if value exists in 2D array

Lets say I have a 2D array of objects. How does one check to see if an object exists in the 2D array without looping. I don’t know if 2D arrays allow me to do so, nor do I know if it has a function such as Exists() or Contains().

var x = 2;
var y = 3;
var allObjects = new GameObject[x,y];
for (var a = 0; a < x; a++) {
	for (var b = 0; b < y; b++) {
 		// Assign objects to 2D array
		allObjects[a,b] = ...;
	}
}

// I get this message: RankException: Only single dimension arrays are supported.
if (object in allObjects) {
	print('Hi! I'm in here!');
} else {
	print("You've got the wrong object!");
}

Probably, it is necessary to write the function of check. Can there were small errors as I program on CSharp:

 private var allObjects:GameObject[ , ] = null;

 function Start() {
  var x = 2;
  var y = 3;
  allObjects = new GameObject[x,y];
  for (var a = 0; a < x; a++) {
   for (var b = 0; b < y; b++) {
    // Assign objects to 2D array
    allObjects[a,b] = ...;
   }
  }
  ... 
  var mygmo: GameObject =...; //any object
  if (checkArr(mygmo)) {
   print("Hi! I'm in here!");
  } else {
   print("You've got the wrong object!");
  }
 }

 //Function for checks object in array
 function checkArr(gmo: GameObject): boolean {
  for(var i:int = 0; i <= allObjects.GetUpperBound(0); i++) {
   for(var j:int = 0; j <= allObjects.GetUpperBound(1); j++) {
    if (gmo == allObjects[i, j]) {
     return true;
    }
   }
  }
  return false;
 }

Or maybe create check function with foreach(CSharp) from msdn help:

 function checkArr(gmo: GameObject): boolean {
  for(var i: GameObject in allObjects) {
   if (gmo == i) {
     return true;
   }
  }
  return false;
 }