How to I get pointer to an Array and cast to a void * and back ?

[seany via Digitalmars-d-learn]

I have a struct :

    struct a {
       int i;
       // some more stuff ...
    }
In a Class, I define public global `void * dataSet; `

In a function `f`, of the same class:  i call :

    void f() {
    a[] rd_flattened;   
    a[] * rd;   

    // DO SOME WORK HERE ....

    this.dataSet = & rd_flattened;  
    rd = cast (a [] *)  dataSet;

    write("length of rd is : "); writeln((*rd).length); // <--- 
this works..
    // do some work on rd

    this.dataSet = rd;
    rd = cast (field.rawData [] *)  dataSet;

    write("length of rd for a second time is : ");
    writeln((*rd).length); // <--- this ALSO works..
    }

Now outside `f`, in the same class, i call :

    void f2() {

    f();

    a[] *aa ;
    aa = cast (a [] *)  this.dataSet; // recall dataset is public 
global
    // if i print the address of this.dataSet here, this is the 
same as inside f()
    write("after calling f, count is: "); writeln((*aa).length); 
readln();
    // here the situation completely blows up . the length is 
wrong.
    }


I need some help here. Sorry, can't post code. It is proprietary.

What is causing this issue ?

thank you.