Default string value... empty? (C#)

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I've declared a public array of strings in my class without assigning values to them. I intend to enter them for each object in Unity's inspector pane. I won't always use the full array (some objects will have less options associated with them,) so I loop through it, and when it finds the first null element in the array it sets int usableLength to that index and stops looping.

Strangely, I found that usableLength always remained at 0. But if I use if (array[x].Equals("")), or IsNullOrEmpty for that matter, it works. I thought C# was supposed to initialize all types to null by default? It's not preventing me from making progress now that I've figured it out, but I'm curious as to why.

Answer 1

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Answer by DannyB · Sep 10, 2013 at 11:26 AM

I believe this is what is going on:

Uninitialized strings in C# will have a null default value.
Uninitialized public strings in Unity (or rather, in a MonoBehavior) will have an empty value.

This demonstrates:

 string myString;
 string[] myStrings;
 
 public string myPublic;
 public string[] myPublics;

 void Start() {
     myStrings = new string[2];
     Debug.Log(myString);     // null
     Debug.Log(myStrings[0]); // null
     Debug.Log(myPublic);     // ""
     Debug.Log(myPublics[0]); // ""
 }

And, as discussed in the comments, I would try to avoid having arrays with "holes". You can either use the inspector array size, or if it does not need to be inspector-exposed, use a generic List instead.

Finally - if you still prefer (or must) keep an array with holes, then you already found your answer. It would be item == "" if its a public inspector array, or item == null and in any case, you better off using IsNullOrEmpty.

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TruffelsAndOranges · Sep 28, 2015 at 10:21 AM 1

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Wow that's interesting. I had a bug that was an implication of Unity setting public strings to another default value than the one I had given it. Thank you for spotting it for me!

Answer 2

Answer by bezier · Jul 28, 2021 at 03:08 AM

Monobehaviour's public fields will have serialization once they get involved in some prefabs. That's why they got objects assigned when you check them in Editor or Player.

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Default string value... empty? (C#)

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