UT_FloatArray fdata; 
UT_Vector3Array vdata; 

GA_Offset ptoff; 
GA_FOR_ALL_PTOFF(gdp, ptoff) 
{ 
    // Fetch array value 
    aif->get(attrib, ptoff, fdata); 

    // Convert UT_FloatArray to UT_Vector3Array 
    // NOTE: /3 for non-negative integers rounds down 
    // if fdata.size() isn't a multiple of 3, so it's safe for that possibility. 
    int vsize = fdata.size()/3; 
    vdata.setSize(vsize); 
    for (exint vi = 0, fi = 0; vi < vsize; ++vi, fi+=3) { 
        vdata[vi] = UT_Vector3(fdata[fi+0],fdata[fi+1],fdata[fi+2]); 
    } 

    // Do something with the vectors 
    for (exint vi = 0; vi < vsize; ++vi) { 
        // This is just an example of something to do 
        vdata[vi] *= 0.5f; 
    } 

    // Convert UT_Vector3Array to UT_FloatArray 
    for (exint vi = 0, fi = 0; vi < vsize; ++vi, fi+=3) { 
        fdata[fi+0] = vdata[vi][0]; // x 
        fdata[fi+1] = vdata[vi][1]; // y 
        fdata[fi+2] = vdata[vi][2]; // z 
    } 

    // Write back 
    aif->set(attrib, ptoff, fdata); 
}