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1234567

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what's the difference function and sub programs? under what situation do u use which one of them?

what's the difference between data validity, and data integrity?
give examples to illustrate ur response.

thank u
 

Milly

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No idea about the second one... but I think I can answer the first :)

Functions and procedures (sub programs... whatever) are similar in that they can both be called by higher level modules - the difference is that a function returns values by setting the value of the function itself (so it can only return one value) whereas a procedure returns values through parameters. Also a function is always used as part of an expression - for example y = square(x) - whereas procedures are always called on their own. That's about all I can think of... I hope that explains it.

There's a good example in Sam D's textbook (planning and designing chapter).
 
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user

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and i can answer the second!

I think

data validation is where you check the data that has been entered to make sure that it's correct

eg making sure that letters have not been entered into a postcode field or something

data integrity is the correctness of the data, how accurate it is. The actual data, not the data form. eg whether someone's date of birth is correct.
 

Milly

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Okay, this is the definition of data integrity from Webopedia (you were right user :p )

Refers to the correctness of data. Data integrity can be compromised in a number of ways:
- Human errors when data is entered
- Errors that occur when data is transmitted from one computer to another
- Software bugs or viruses
- Hardware malfunctions, such as disk crashes
- Natural disasters, such as fires and floods

There are many ways to minimize these threats to data integrity. These include:
- Backing up data regularly
- Controlling access to data via security mechanisms
- Designing user interfaces that prevent the input of invalid data(ie. data validation so data validity and data integrity are linked :) )
- Using error detection and correction software when transmitting data
 

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