Question

I’m actually searching for a guidline, how to document multiple exceptions in a public method inside a C#-DLL.

example:

/// <summary>
/// This method does something
/// </summary>
/// <param name="p_Parameter1">First parameter</param>
/// <param name="p_Parameter2">Second parameter</param>
/// <param name="p_Number">A number</param>
/// <exception cref="ArgumentNullException">
/// Thrown if p_Parameter1 is null</exception>
/// <exception cref="ArgumentNullException">
/// Thrown if p_Parameter2 is null</exception>
/// <exception cref="ArgumentNullException">
/// Thrown if any element of p_Parameter2 is null</exception>
/// <exception cref="ArgumentOutOfRangeException">
/// Thrown if p_Number is below or equal 0</exception>
/// <returns>A object</returns>

public static object DoSomething(
    object p_Parameter1, IList<object> p_Parameter2, 
    object p_Parameter3, int p_Number)
{
    if(p_Parameter1 == null)
        throw new ArgumentNullException(
            paramName:"p_Parameter1", 
            message:"Parameter is needed");
    if (p_Parameter2 == null)
        throw new ArgumentNullException(
            paramName: "p_Parameter2", 
            message: "Parameter is needed");

    for (int i = 0; i < p_Parameter2.Count; i++)
    {
        if(p_Parameter2[i] == null)
            throw new ArgumentNullException(
                paramName: String.Format("p_Parameter2[{0}]", i),
                message: "All elements have to be initialized");
    }

    if(p_Number < 0)
        throw new ArgumentOutOfRangeException(
            paramName: "p_Number", 
            message: "Parameter should be bigger then zero");

    var returnValue = new object();

    // do something where p_Parameter3 == null is allowed

    return returnValue;
}

Is it the right way to document those exceptions? Should I add one exception-tag for each case, or should I add only one for all Parameters for which null-values ar not allowed?

/// <exception cref="ArgumentNullException">
/// Thrown if p_Parameter1, p_Parameter2
/// or any element of p_Parameter2 are null</exception>

Answer 1

I would definitely group the exceptions by type, ie Thrown if p_Parameter1, p_Parameter2
or any element of p_Parameter2 are null.

As a reference, look at the documentation at MSDN. An example:

ArgumentNullException   |   Either path, contents, or encoding is null.