C# Using structs for Range variable type
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I am trying to make a struct for a range variable (minimum, maximum) with a few members like to know if between values.

Right now my struct looks like this:

    public struct numRange
    {
    	float maximum;
    	float minimum;
    
    	public numRange(float min, float max) 
    	{
    		this.maximum = max;
    		this.minimum = min;
    	}
    
    	public bool isBetween(float value)
    	{
    		if (value < maximum && value > minimum)
    			return true;
    
    		return false;
    	}
    }

I want to be able to make number ranges by 

    numRange test = new numRange(15, 20);


The whole point of making this range variable type is to make a map key dictionary like:

    public Dictionary<numRange, Color> mapKey = new Dictionary<numRange, Color>();
    numRange test = new numRange(15, terrainGroundLevel);
    mapKey.Add(test, Color.Orange);

Is this the best way to go about it? Also it doesn't like when I try to add something to mapKey. Says there is invalid tokens such as ',' ')' '('