Can't create static variable inside a static method?

Why won't this work?

public static int[] GetListOfAllDaysF开发者_StackOverflow中文版orMonths()
{
    static int[] MonthDays = new int[] {1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31};

    return MonthDays;
}

I had to move the variable declaration outside of the method:

    static int[] MonthDays = new int[] {1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31};
public static int[] GetListOfAllDaysForMonths()
{
    return MonthDays;
}

Also, so by creating it this way, we only have one instance of this array floating around in memory? This method sits inside a static class.

C# doesn't support static locals at all. Anything static needs to be a member of a type or a type itself (ie, static class).

Btw, VB.Net does have support for static locals, but it's accomplished by re-writing your code at compile time to move the variable to the type level (and lock the initial assignment with the Monitor class for basic thread safety).

[post-accept addendum]
Personally, your code sample looks meaningless to me unless you tie it to a real month. I'd do something like this:

public static IEnumerable<DateTime> GetDaysInMonth(DateTime d)
{
    d = new DateTime(d.Year, d.Month, 1);
    return Enumerable.Range(0, DateTime.DaysInMonth(d.Year, d.Month))
             .Select(i => d.AddDays(i) );
}

Note also that I'm not using an array. Arrays should be avoided in .Net, unless you really know why you're using an array instead of something else.

You can only create static variables in the class/struct scope. They are static, meaning they are defined on the type (not the method).

This is how C# uses the term "static", which is different from how "static" is used in some other languages.

What would be the scope of that static variable declared within the method? I don't think CLR supports method static variables, does it?

Well, apart from it not being supported, why would you want to? If you need to define something inside a method, it has local scope, and clearly doesn't need anything more than that.