How to set an array parameter with variable size for simulink model

I want to set an array parameter can be filled by the model user (who is also a developer) in the generated source file (like .h file in C language) and the length of this array is not limited. And then, I can get the size of this array in the model and traverse it.

For example, the model generate a source file as:

const int THE_ARRAY_PARAMETER[] = { 1, 2, 3 };

The model user can filled it, such as:

const int THE_ARRAY_PARAMETER[] = { 10, 20, 30, 40, 50 };

I can get the size of THE_ARRAY_PARAMETER and traverse it in the model.

But I don't know how to set this kinds of array parameter in the model and how to get the size of the array.