OPM/opm-core — pull request #92 by bska (2012-11-07 16:26:45+00:00)
Title: Fix signed-vs-unsigned comparison warning

The existing code compared the output of `data->size()`, which is a
```c++
std::vector::size_type
```
(typically `std::size_t`) and therefore an unsigned integer type to the
number `grid.number_of_cells` which is a (signed) `int`.

This leads to an annoying warning when increasing the
warning level in GCC.

While here, also insert code to verify that the `stride` is a positive
number lest the subsequent assignment loop reference `(*data)` elements
out of bounds.