I've found that when using ocicolumnprecision or oci_field_precision it will not show you the decimal places if you are are reading from tables with decimals. You can use ocicolumnscale or oci_field_scale to find the decimal.
if( ocicolumnscale($R, $i ) > 0 )
{
$int_decimal = ocicolumnscale($R, $i );
$int_length = ocicolumnprecision($R, $i) - $int_decimal;
}