vtkAbstractArray::Resize behaviour

[drpeterfranz (Peter Franz)]

The vtkAbstractArray::Resize() method states:

Resize the array to the requested number of tuples and preserve data.

Increasing the array size may allocate extra memory beyond what was requested. MaxId will not be modified when increasing array size. Decreasing the array size will trim memory to the requested size and may update MaxId if the valid id range is truncated. Requesting an array size of 0 will free all memory. Returns 1 if resizing succeeded and 0 otherwise.

So indeed, when I resize an array I get

double_array->Resize(5);
vtkIdType double_tuples = double_array->GetNumberOfTuples(); // yields 0
vtkIdType double_vals = double_array->GetNumberOfValues(); // yields 0

So what should I do if I have an array with existing data which I want to preserve, but create additional space beyond it. After resizing I want GetNumberOfTuples() to return the number to which I have resized the array. So would

double_array->Resize(5);
double_array->SetNumberOfTuples(5);

be the correct way to achieve this?

[Yohann_Bearzi]

You’re correct. You need to call Resize before calling SetNumberOfTuples.

[drpeterfranz (Peter Franz)]

Thanks!