[email protected]

or reply to this message, thanks!

aky

So what part of what you just said don't you understand how to do - and is it b/c you don't get the math, the idea, or you don't know how to do it in TP?

If you give me the specifics of what you need, but not the whole problem, then I can tell you how to do that.

Have you written any code yet (prior to this - or also have you started writing code for this problem)?
Even pseudocode?

Ok i'll be more specific.. my question is i dont know how to use the function. I am suppose to use a function to determine if a # is prime or not. I just need help getting started... a kick start!

aky

Here is thought process I would go through on writing such a thing:

I need to talk to the user of this program, I need output text to the screen that will let them know they need to perform an action in order for this to work. I then need to take ina value, and then store it in a variable. I then need to take this stored value and look at it and do a calculation on it. Once I've determined if this is prime or not, then I need to, one last time, write to the screen and let the user know to which side the outcome resulted in - prime or not.
so:
1) learn how to write to the screen in TP. in javascript you might use the write(x) function, where x is the string you want output to wherever you are dumping it (usually to the document object or a div) - in TP there is an equivalent.
2) then figure out how to take a value in. in C++, if I recall correctly, there was cin and cout - cout was anything you were writing to the screen, and cin were values you were pulling in.
3) dump that value into a variable.
4) pass that variable into your prime function and that would presumable return true or false.
5) then, based on what is returned, you will the again call the TP function that allows you to output text to the screen and let the user know the outcome.

do you have a textbook or manual for the class?

they dont provide us with the function... they just tell us that we have to use one...

also i know how to do everything you mentioned except how to write the function and how to calculate if the number is prime or not.

aky

quote:

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Originally posted by aky:
you have mail

they dont provide us with the function... they just tell us that we have to use one...

also i know how to do everything you mentioned except how to write the function and how to calculate if the number is prime or not.

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I checked my e-mail but something went wrong and hushmail wouldn't let me open the letter.

okay, well a function is just a chunk of code that doesn't get run unless you call it - and when you call it, you can pass it things, it will then do stuff, and it can then return suff back to you.

It has been awhile since I wrote anything in TP (it sucks), but I think it is called a procedure in TP - so look that up in your book and/or for the class.

pretty much you are going to have a funtion like so - with the working parts between
isPrime(i:interger);
end;

for the working parts you will want to make use of a built in math function called "mod" - modular arithmatic outputs the remainder of division. so if I said 4 mod 2 - that would output 0. if I said 7 mod 2 - that would output 1.
think this through and you can then do a loop and figure out the primes.
(hint: you are taking in an integer. loop through 1 all the way up to you integer and do a mod against it. if you ever get 0 returned, then you know that it is evenly divisible by something, and therefore not prime - so you can then exit your function and return to the screen that you aren't prime. if you get all the way through the loop and no 0's returned from mod - then you know it is prime.)

please help, you seem like the only one who knows about TP!!!

aky

Now look up how to do loops - a for loop is probably what you want.

I'll write this in pseudocode here - if you want I can write it in some other language (even can be easily done in javascript - which might as well be pseudocode it is so easy) for you too - I just don't feel that I should write out the code in TP for you b/c that is just doing your work for you.

function isPrime(i)
for x=2 to i-1 do
y = i mod x
if y equals 0 then
isPrime returns false
exit function
end if
loop for
return true
end function

inputValue = readValue(X)
outputValue = isPrime(inputValue)
writeValue(outoutValue)

The general concept here is the same as what I covered in the hint in my last post.
you want to take in a number. then do a mod on it for all numbers from 2 up to itself minus one (1 and itself are obviously going to return 0) - if anything in there also returns 0, then you can end right then b/c it isn't prime. if it never returns 0, then you know it is prime. (mod will only return zero if it goes in evenly - like 2 goes into 4 twice with no remainder, 3 goes into 7 twice with a remainder of 1.)

That really should do it there. I'm not going to write the TP code for you... you should learn... I a frickin hate TP.

aky

i just cant get it.... if you can help me further that would be awesome. But if not that's ok too... i just need an example to look at then i can refer to it... i'm not going to copy it because then i'll flunk the exam... the best way to learn (for me) is from similar examples.... hope you can help...

but thanks for everything so far....

aky

procedure isPrime(i:integer);
for x=2 to i-1;
modValue = i mod x;
if modValue equals 0 then;
return false;
exit procedure;
end;
end;
return true;
end;

writeln("Enter a number:");
readln(sPassedNum);
outputValue = isPrime(sPassedNum);
writeline(outputValue);

like I said, I haven't done the TP in a long time, so I don't know the syntax to exit a function, and I don't remember how the for loops, or the if statements are formed - but it is a lot like what I have above.
do you not have a book - look in the back at the index and you will find that it will point to the section of what you want. look in the back for "if" and it should tell you where the pages that discuss if statements are and the proper syntax.

that really should do it.

so it would look like this to the user:

Enter a number: (they enter 5)
true

or

Enter a number: (they enter 6)
false

you could also look at the boolean (the true or false) and do a check on it, if it is t or f, then output a certain string so that the user gets more info than just t or f.

good luck - that is all I can do for you.

aky