Question

The function WriteStartAttribute can be called with 1, 2 or 3 strings as arguments. The amount I want to call it with is dependent on the amount of arguments in writeInfo. To clarify, I want to do the following using a loop:

if (writeInfo.Count == 2)
{
    writer.WriteStartAttribute(writeInfo[1]);
}
else if (writeInfo.Count == 3)
{
    writer.WriteStartAttribute(writeInfo[1], writeInfo[2]);
}
else if (writeInfo.Count == 4)
{
    writer.WriteStartAttribute(writeInfo[1], writeInfo[2], writeInfo[4]);
}

I tried it using an array (and a List) like this:

for (int i = 0; writeInfo.Count() - 1 < i; i += 1)
{
     argumentList[i] = writeInfo[i + 1];
}
writer.WriteStartAttribute(argumentList);

However, because no overload accepts an array (or a List) this does not work.

How can I call a function with differing amount of arguments using a loop?

Answer 1

Assuming this is the XmlTextWriter.WriteStartAttribute, it doesn’t accept params so you’ll have to manually handle it.

Create your own params method, and then put your if statements in there:

void WriteStartAttribute(params string[] values) 
{
     if (values.Length > 4 || values.Length < 2) throw new ArgumentException();
     if (values.Count == 2)
     {
        writer.WriteStartAttribute(values[1]);
     }
     else if (values.Count == 3)
     {
        writer.WriteStartAttribute(values[1], values[2]);
     }
     else if (writeInfo.Count == 4)
     {
        writer.WriteStartAttribute(values[1], values[2], values[4]);
     }
  }

Then call that in your loop:

WriteStartAttributes(writeInfo);

Bonus points for making it an extension method:

public static void WriteStartAttribute(this XmlTextWriter writer, params string[] values) 
...

writer.WriteStartAttributes(writeInfo);