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WJEC A2 Computing CG3 - Tuesday 23rd June 2015 [Exam Discussion Thread]

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Haha i have no idea xD but it just goes to show you might as well write something even if you think its stupid as it could be in the mark scheme

Saying that, if i was asked why they were better than random i wouldn't know what to write? maybe that they required less processing power but i have no idea, I'm not good at file organisation

Accessing records using the Random/Direct access method is EXTREMELY quick, however once the Disk Blocks get full, and the Overflows get populated.. LOTS of processing is required to shuffle files around and re-allocate dick blocks

Reply 181

CD223

Original post by Async

Depends. Let's say you have a 250MB file loaded into memory and you want to pass it to another sub routine to do some checks that doesn't require you to change the object then passing By Reference would be the most sensible thing to do because it doesn't create a brand new copy of the object, therefore saving memory space and processing power. By passing by reference, you're simply just passing the pointer/memory location to the 250MB object.

So passing by reference is less memory-intensive?

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Reply 182

Async

Original post by CD223

So passing by reference is less memory-intensive?

Posted from TSR Mobile

I'm talking from a C++ standpoint, from my understanding, a pointer is passed in C++ and that resembles ByRef as it's just passing the pointer of the object.

But to be honest, I don't understand why ByRef would be more memory intensive than ByVal. ByVal copies the whole object whereas ByRef copies only the reference/pointer of the object. Therefore shouldn't ByRef be less IO intensive?

Reply 183

Async

Original post by CD223

So passing by reference is less memory-intensive?

Posted from TSR Mobile

Yes it's less memory intensive to pass by reference
https://msdn.microsoft.com/en-us/library/ddck1z30.aspx

Reply 184

Vents

Original post by Async

Therefore shouldn't ByRef be less IO intensive?

I was taking this from the assumption that procedures could be modifying the object passed by reference, and if you are going to recurse a procedure many times modifying every time you're going to have a high IO.

But as you said, this depends on a range of factors, and from a memory usage perspective pass by ref every time.

(edited 8 years ago)

Reply 185

Async

Original post by Enrico2285

Oh yeah for sure! Recursive calls are IO intensive, it's only cause we all have good CPUs noways that we don't notice.

But logically speaking, ByReference is more IO efficient when passing large objects as it only points to the existing object in memory rather than creating a brand new replica.

Reply 186

CD223

Original post by Async

Ah, thanks for that.

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Reply 187

Vents

In a car factory, a number of tasks are carried out by robots. Explain what ismeant by a robot and describe how robots might be used in a car factory. Discussthe benefits and drawbacks of using robots for the owners of the car factory

Sigh...

Reply 188

CD223

Original post by Enrico2285

That question is annoying. Have you seen the one on weather forecasting? Lol.

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Reply 189

actanide

Original post by Enrico2285

Hate that kind of questions, but then again these are easy marks and anyone can get the marks, even without computing knowledge, so I can't complain

Reply 190

JordanEvans96

Does anyone know any drawbacks to forms dialogue?

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Reply 191

actanide

Original post by JordanEvans96

Does anyone know any drawbacks to forms dialogue?

Posted from TSR Mobile

very restricted , some entries might not be allowed but still be true

Reply 192

unknown192

Could someone explain Masking? What is the use of it?

Reply 193

CD223

Original post by unknown192

Could someone explain Masking? What is the use of it?

Logical operators such as AND can be used to "mask" numbers for a variety of applications. Using a mask - a binary number such as 00001000 - with the AND operator, you can determine whether a certain bit is a zero or a one. In the case of the mask above, this would discover the value of the 5th bit.

Masking can also be used to convert ASCII codes into binary numbers. See below:
ImageUploadedByStudent Room1434887994.218502.jpg