Is there a function to check if an object is a builtin data type?

Question

I would like to see if an object is a builtin data type in C#

I don't want to check against all of them if possible.
That is, I don't want to do this:

        Object foo = 3;
        Type type_of_foo = foo.GetType();
        if (type_of_foo == typeof(string))
        {
            ...
        }
        else if (type_of_foo == typeof(int))
        {
            ...
        }
        ...

Update

I'm trying to recursively create a PropertyDescriptorCollection where the PropertyDescriptor types might not be builtin values. So I wanted to do something like this (note: this doesn't work yet, but I'm working on it):

    public override PropertyDescriptorCollection GetProperties(Attribute[] attributes)
    {
        PropertyDescriptorCollection cols = base.GetProperties(attributes);

        List<PropertyDescriptor> list_of_properties_desc = CreatePDList(cols);
        return new PropertyDescriptorCollection(list_of_properties_desc.ToArray());
    }

    private List<PropertyDescriptor> CreatePDList(PropertyDescriptorCollection dpCollection)
    {
        List<PropertyDescriptor> list_of_properties_desc = new List<PropertyDescriptor>();
        foreach (PropertyDescriptor pd in dpCollection)
        {
            if (IsBulitin(pd.PropertyType))
            {
                list_of_properties_desc.Add(pd);
            }
            else
            {
                list_of_properties_desc.AddRange(CreatePDList(pd.GetChildProperties()));
            }
        }
        return list_of_properties_desc;
    }

    // This was the orginal posted answer to my above question
    private bool IsBulitin(Type inType)
    {
        return inType.IsPrimitive || inType == typeof(string) || inType == typeof(object);
    }

Answer 1

Not directly but you can do the following simplified check

public bool IsBulitin(object o) {
  var type = o.GetType();
  return (type.IsPrimitive && type != typeof(IntPtr) && type != typeof(UIntPtr))
        || type == typeof(string) 
        || type == typeof(object) 
        || type == typeof(Decimal);
}

The IsPrimitive check will catch everything but string, object and decimal.

EDIT

While this method works, I would prefer Jon's solution. The reason is simple, check the number of edits I had to make to my solution because of the types I forgot were or were not primitives. Easier to just list them all out explicitly in a set.

Answer 2

Well, one easy way is to just explicitly list them in a set, e.g.

static readonly HashSet<Type> BuiltInTypes = new HashSet<Type>
    (typeof(object), typeof(string), typeof(int) ... };

...


if (BuiltInTypes.Contains(typeOfFoo))
{
    ...
}

I have to ask why it's important though - I can understand how it might make a difference if it's a .NET primitive type, but could you explain why you would want your application to behave differently if it's one of the ones for C# itself? Is this for a development tool?

Depending on the answer to that question, you might want to consider the situation with dynamic in C# 4 - which isn't a type at execution time as such, but is System.Object + an attribute when applied to a method parameter etc.