What is true between data modeling and the formatting of the data?
Answers
A data model defines concepts used in the computer system and their semantic relationship to concepts in the world outside. For example: The HOTEL entity represents a single hotel, hostel, or cruise ship where travellers can book accommodation.
A data format defines how these concepts in the computer system are represented using bits and bytes (perhaps via intermediate layers such as XML or JSON, because if you define it in terms of XML or JSON, then the representation in bits and bytes is implicit). For example: the HOTEL entity is represented as an XML
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Explanation:
Static
allocation:
Advantages:
1. Static
allocation is done at compile time when you know the size of the array.
2. The
memory size allocated to “data” is static. But it is possible to change content
of a static structure without increasing the memory space allocated to it.
3. Global
variables are declared “ahead of time,” such as fixed array.
4. Lifetime
of Static allocation is the entire runtime of program.
5. It
has efficient execution time
Disadvantages:
1. In
case more static data space is declared than needed, there is waste of space.
2. In
case less static space is declared than needed, then it becomes impossible to
expand this fixed size during run time.
Dynamic Allocation:
Advantages:
·
Dynamic Allocation
is done at run time.
·
Data structures can grow and shrink to fit
changing data requirements.
·
We can
allocate (create) additional storage whenever we need them.
·
We can de-allocate (free/delete) dynamic space
whenever we are done with them.
·
Thus we can always have exactly the amount of
space required - no more, no less.
Disadvantages:
·
As the memory is allocated during runtime, it requires more
time.
·
Memory needs to be freed by the user when done. This is important as it is more likely to
turn into bugs that are difficult to find.