Unity3D: Automatic target according to price - unity3d

Question

I've been working on a simulator in Unity3D and i need a customer object to be able to automatically find the shop object with the lowest price.
I've done a little testing on this myself and found it to be rather difficult to achive. So i was hoping someone could help me tweak my code a bit further in the right direction? :)
Here's the code i've got so far:
var cityName : String;
var shopScript : MarketScript;
function FindShopPlace () : GameObject //Make a queueing system
{
var max : float;
var target : GameObject;
var gos : GameObject[];
var goScript : MarketScript;
gos = GameObject.FindGameObjectsWithTag("market");
for (var go : GameObject in gos)
{
goScript = go.GetComponent(MarketScript);
if (goScript.cityName == cityName)
{
if (goScript.resalePrice >= max && goScript.cityName == cityName)
{
max = goScript.resalePrice;
}
if (goScript.resalePrice < max && goScript.cityName == cityName)
{
print ("test");
target = go;
}
}
}
shopScript = target.GetComponent(MarketScript);
return target;
}
Currently with this code, the target is never found and assigned. I get the following NullReferenceException from line number 3 from the bottom:
NullReferenceException: Object reference not set to an instance of an
object ConsumerScript.FindShopPlace () (at
Assets/_MyAssets/_Scripts/ConsumerScript.js:268) ConsumerScript.Update
() (at Assets/_MyAssets/_Scripts/ConsumerScript.js:96)

Answer 1

You get a NullReferenceException because target was never set to any object.
What you are doing in your loop is (1) finding the maximum price and (2) finding the last Object after maximum that is smaller than the maximum.
So if your prices in order are 1, 2, 3 target will never be set because in each step you are setting the maximum to the new value and are never setting target. Even when set its not necessarily the cheapest. Consider the prices 1, 3, 2.
First Step: Set maximum to 1
Second Step: Set maximum to 3
Third Step: Set target to the GameObject with price 2
If you get errors like this try out simple examples like this to get to the bottom of things. Also you are using the variable maximum(comparing the first time) without ever setting it to anything, not sure if this works in Javascript(it might) but its bad practice
What you really want isnt finding the maximum price or minimum price but the GameObject with the lowest resalePrice.
var min : float;
var success : boolean;
var firstHit : boolean;
...
success = false;
firstHit = true;
for (var go : GameObject in gos)
{
goScript = go.GetComponent(MarketScript);
if (goScript.cityName == cityName)
{
success = true;
if(firstHit) // alternatively to this would be to set minimum to a value that is higher than every possible price ( thats also what i meant with you shouldnt use max without setting it to anything)
{
min = goScript.resalePrice;
target = go;
}
else
{
if (goScript.resalePrice < min )
{
min = goScript.resalePrice;
target = go;
}
}
}
}
if(success)
{
shopScript = target.GetComponent(MarketScript);
return target;
}
else
{
// TODO: handle the case that there isnt a shop in the city.
// Maybe give an error Message with Debug.Log if this isnt supposed to happen
return null;
}