thanks edward,
okay with passing a single value by reference, but what i need to do is pass in an array, such as an array of floats.

Here's the C++ declaration:
DLL_FUNCTION int ShapeVerifyEntryPoint( char *shapeId, int numDims, float dims[MAX_DIM] )


Here's my fox code:
DECLARE INTEGER ShapeVerifyEntryPoint IN shapedll.dll AS ShapeVerify STRING @shapeid, INTEGER numdims, DOUBLE[10] the_dims

#DEFINE MAX_DIMS 10

LOCAL lcShapeID, lnNumDims, laDims, lnReturn

lcShapeID = "52"
lnNumDims = 1
DIMENSION laDims[lnNumDims]
laDims[1] = 20.0

lnReturn = ShapeVerify(lcShapeID, lnNumDims, laDims)

RETURN

The results of running this is that FoxPro bombs.