GenericStack hold an example of a template class.

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Accessing a member of a struct Rec that is itself an array element:
Assume we want A[i].data
1. Start at base address of array A.
2. Add i*sizeof(Rec)
3. Add the sizes of the members preceding data.

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Some data types were devised with the purpose of conserving memory. Two of them are union and variant record....

Union
A union is declared memory designated to hold one of several possible values. 
  A union variable looks like a record, but the designated members all share memory, 
	i.e. only one can be in use at any one time. All members represent the same l-value

Variant Record
A variant record is one where a portion of the record is tantamount a union.
- The particular variant is chosen via a 'tag field'