C# empty arraylist string arrays and pass them as parameters

Question

In my winform application, I have an arraylist containing a dynamic number of string arrays. I need to somehow remove each string array from the array list and then use these string arrays as parameters for a function. The number of string arrays in the arraylist can vary as they are created dynamically.

The method declaration:

public void mychartbuilder(string[] Column1, string[] Column2 = null, string[] Column3 = null, string[] Column4 = null)

The following is causing the biggest headache. Since there is a dynamic number of arrays in the list, I can't determine how to pull them out and then send them into the function as parameters.

foreach (string[] myarray in myArrayList)
    {
        string[] copy1 = new string[rcounter];
    }
mymethods.mychartbuilder(//string array parameters will go here)

Thanks in advance.

Is there any reason you're not just passing the entire ArrayList to the the method "mychartbuilder"? — Hugo
– Hugo, Commented Mar 28, 2012 at 2:34

Servy · Accepted Answer · 2012-03-28 02:48:28Z

1

while(arrayList.Count < 4)
{
  arrayList.Add(null);
}

mychartbuilder((string[])arrayList[0], (string[])arrayList[1], (string[])arrayList[2], (string[])arrayList[3]);

Note that you can use List<string[]> rather than an ArrayList to avoid all of the casting.

answered Mar 28, 2012 at 2:48

Servy

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4 Comments

HendPro12 Over a year ago

Not sure I follow you. It looks as if your code will replace my string arrays with null. Is that correct? I am not wanting to do that. Then it appears you are casting each element of the list as a string array. That appears as if it would work but I need the last three parameters to be optional.

Servy Over a year ago

It won't replace anything with null. If there is 1 item in the list the while loop will be run three times, meaning there will be one array and three nulls and it will pass an array as the first param, and null to the rest, which is exactly the same as calling the method with just one array since the other parameters are optional (you just set them to null). If the arrayList had 3 items only one null would be added, and all but the last parameters would be non-null in the method call. Basically it ignores that the method handles optional arguments and defaults the parameters early.

Servy Over a year ago

If you want to actually utilize the fact that the method has optional parameters you'll need to have 4 if statements, basically if list.count < 2, else if list.count < 3, and calling the method with the appropriate number of arguments. It would be very ugly. My way is much shorter and equally effective.

HendPro12 Over a year ago

You sir are a genius. Thank you! Works perfectly. Much simpler solution than I was expecting to find.

Simon Wang · Accepted Answer · 2012-03-28 02:34:29Z

0

I think you can go with reflection to call it: http://msdn.microsoft.com/en-us/library/a89hcwhh.aspx

public Object Invoke(
Object obj,
Object[] parameters
)

The invoke will take multi parameters and all you need is change your ArrayList to Object[]

answered Mar 28, 2012 at 2:34

Simon Wang

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