c# array initialization "cannot reference the non-static field, method or property" error

Question

I'm a newbie programmer and learn at the moment c# and Unity3d.

I got a problem, as i tried to initialize an array of public float variables.

    [Range (0,1)]
public float appleProbability = 0.4f ;

[Range (0,1)]
public float fishProbability = 0.2f ;

[Range (0,1)]
public float cheeseProbability = 0.10f ;

[Range (0,1)]
public float poopProbability = 0.14f ;

[Range (0,1)]
public float bombProbability = 0.14f ;

[Range (0,1)]
public float starProbability = 0.02f ;

private float[] probs = new float[] {appleProbability, fishProbability, cheeseProbability, poopProbability, bombProbability, starProbability};

(The [Range (0,1)] should make a slider in the inspector of the script in unity, so you can manipulate the public variable between 0 and 1 with the slider.)

I get the error: "A field initializer cannot reference the non-static field, method or property 'GameManager.appleProbability'." (the same for the other variables)

I tried this code for a test:

    public int blub = 1;
public int hub = 2;

private int[] bla = new int[3];

bla[0] = blub;

but I get the error: "Array size cannot be specified in a variable declaration (try initializing with a 'new' expression)."

Strange thing is, that the first error dissapears, when I get the second error, also I haven't changed the code from the first error.

I've read this question all possible c# array initialization syntaxes but it doesn't help.

I'm feeling a little bit stupid, but I don't get the error :/

score 1 · Answer 1 · answered Nov 30 '14 at 23:41

The compile tells you precisely what's happening - you cannot reference non-static fields in the array initializer.

You have two options to resolve this:

If it is OK with you to make probabilities static, make them static, or even const of they are readonly.
Otherwise, move initialization into the constructor of your class.

Here is the first option:

[Range (0,1)]
public static float fishProbability = 0.2f;
...

Here is the second option:

private float[] probs;
public MyClassConstructor() {
    probs = new float[] {appleProbability, fishProbability, cheeseProbability, poopProbability, bombProbability, starProbability};
}

Thanks a lot! So I can only use the static solution, if my class inherit from MonoBehaviour, because Unity doesn't like constructors. I know what a static method or static class is, but I haven't seen it at arrays, so I was confused. — Stephanie Platz, Nov 30 '14 at 23:59

score 1 · Accepted Answer · answered Nov 30 '14 at 23:44

you are trying to set values into an array when those values have not been initialized, you need to either make those values static, hard-code defaults in the array, or initialize those values in the constructor:

[Range (0,1)]
public static float appleProbability = 0.4f ;
[Range (0,1)]
public static float fishProbability = 0.2f ;
[Range (0,1)]
public static float cheeseProbability = 0.10f ;
[Range (0,1)]
public static float poopProbability = 0.14f ;
[Range (0,1)]
public static float bombProbability = 0.14f ;
[Range (0,1)]
public static float starProbability = 0.02f ;
private float[] probs = new float[] {
                       appleProbability, 
                       fishProbability, 
                       cheeseProbability, 
                       poopProbability, 
                       bombProbability, 
                       starProbability};

OR:

[Range (0,1)]
public float appleProbability = 0.4f ;
[Range (0,1)]
public float fishProbability = 0.2f ;
[Range (0,1)]
public float cheeseProbability = 0.10f ;
[Range (0,1)]
public float poopProbability = 0.14f ;
[Range (0,1)]
public float bombProbability = 0.14f ;
[Range (0,1)]
public float starProbability = 0.02f ;
private float[] probs = new float[] {
                       .4f, 
                       .2f, 
                       .10f, 
                       .14f, 
                       .14f, 
                       .02f};

OR:

[Range (0,1)]
public float appleProbability = 0.4f ;
[Range (0,1)]
public float fishProbability = 0.2f ;
[Range (0,1)]
public float cheeseProbability = 0.10f ;
[Range (0,1)]
public float poopProbability = 0.14f ;
[Range (0,1)]
public float bombProbability = 0.14f ;
[Range (0,1)]
public float starProbability = 0.02f ;
private float[] probs;
MyClass()
{
    probs = new float[] {
                       appleProbability, 
                       fishProbability, 
                       cheeseProbability, 
                       poopProbability, 
                       bombProbability, 
                       starProbability};
}

You could also make them const instead of static if they are not going to change.

c# array initialization "cannot reference the non-static field, method or property" error

2 Answers2