How can I find out to which VARIANT type a MATLAB variable is converted?

I have a COM object that expects a variable of type Variant(Optional). I would like to know how MATLAB data types are mapped to COM VARIANT types so that I can pass the correct data.

Answer 1

[MathWorks Support Team]

Most MATLAB data types are mapped to a certain VARIANT type. As of R2010a, there are some unsupported MATLAB types, but limitations are subject to change in newer releases.

The attached component can be used to find out how MATLAB data types are mapped to VARIANT types and to test for different behavior in different releases. Installation and requirement information is included in the ZIP file. The following example shows how to use the component:

 >> varTester = actxserver('VariantTester.Tester')

 varTester =

COM.VariantTester_Tester

 >> varTester.invoke

 TestVariant = string TestVariant(handle, Variant(Optional))

 >> varTester.TestVariant()

 ans =

 VT_ERROR (SCODE)

 >> varTester.TestVariant('Hello world')

 ans =

 VT_BSTR (BSTR)

 >> varTester.TestVariant(12345)

 ans =

 VT_R8 (DOUBLE)

 >> varTester.TestVariant([])

 ans =

 VT_ERROR (SCODE)

 >> varTester.TestVariant([123 456])

 ans =

 VT_ARRAY | VT_R8 (DOUBLE)

 >> varTester.TestVariant({'123' '456'})

 ans =

 VT_ARRAY | VT_VARIANT

 >> varTester.TestVariant(int8(123))

 ans =

 VT_I1 (CHAR)

 >> varTester.TestVariant(int16(123))

 ans =

 VT_I2 (SHORT)

 >> varTester.TestVariant(int32(123))

 ans =

 VT_I4 (LONG)