Trying to set up a loop to count in the following way;
Want it to count 1/3+1/5+1/7...... for a set number of terms
So far its just confusing me as to how I could set this up. Is it possible to have a loop count in this way or could it only count using the same value over an over, eg. +2+2+2+2.......
Thanks
Is this what you want?
Lots of other ways - this should get you started. Sounds like you are just starting. Use this example as a guide, try to do the same thing another way.Code:double fractioncalc( int count ) { /* count is the number of terms 1/1, 1/3,1/5 count = 1 returns 1 Returns double as result must be FP Casting used e.g (double) 1 - for clarity - could use literals instead */ int i; double val = (double) 0; if( count <= 1 ) { return (double) 1; } for( i = 2; i <= count; i++ ) { val += (double) 1 / ( (double) ( 2*count - 1 ) ); } return val; }
This is how I might write the code along the lines of johnggold's example:
In this case the "set number of terms" is straightforward: we're just looping from 1 to n inclusive.Code:/* Compute 1/3 + 1/5 + 1/7 + ... + 1/(2n+1) * Returns result, or 0 if n is non-positive. */ double computeFractionalSum(int n) { double result = 0.0; for (int i = 1; i <= n; ++i) { result += 1.0 / (2 * n + 1); } return result; }
Look up a C++ Reference and learn How To Ask Questions The Smart WayOriginally Posted by Bjarne Stroustrup (2000-10-14)
tsk, tsk
No test for invalid n??. What if n is 0? - loop forever!!!
And you loop once too many!!!! - requirement is for n - not n+1
Also ++i - I know you can do this - not usual method - especially when recommending code for a beginner.
Never re-write code unless the user benefits
It would be interesting to know what code you were looking at to produce such a response. You also might want to fix up your own code.
If I did your homework for you, then you might pass your class without learning how to write a program like this. Then you might graduate and get your degree without learning how to write a program like this. You might become a professional programmer without knowing how to write a program like this. Someday you might work on a project with me without knowing how to write a program like this. Then I would have to do you serious bodily harm. - Jack Klein
Wow. Amazing post.
1. What if n is 0? His code won't loop once and return 0 immediately. All input is defined perfectly: 0 for an n <= 0 and otherwise the result. It even says so in the comments.
2. He doesn't loop once too many. He loops exactly n times.
3. ++i is actually better practice than i++, usually, unless you have very good reason to use i++. This is because for some classes, ++i will be a lot faster than i++, as it avoids a copy. For integers it usually won't matter, though better use the same standard anyway.
Actually, there was nothing wrong with his code. Your code is poorly indented (matter of style, though most will agree with me), and has a lot of useless if's.
Really, the post read like "look how good I am I can write better codez than you". Well, guess what? His code was pretty much perfect, your code isn't, and if you complain about code, at least make sure you know what you complain about. And by the way - you do know you return the wrong result for n = 0, don't you? And that the line casting to double is lousy as well...
I work in a team of six, with six very different styles. We all have tuned beautifiers, which we may use occasionally on very complex code - mostly we read each others style with no problem.
I first used beautifiers in the 80's - they are freely available - so why make such a big fuss about style - nothing better to talk about I suppose.
Remember the original enquiry is from a beginner. It is important to be verbose at the beginning, and the explicit checking for invalid values first is good practice, whether or not the main body can or cannot handle it.
Instead of picking points, why not think about how a beginner must feel with all your sniping - not helpful is it.
Never re-write code unless the user benefits
I can't even be bothered to reply to the rest of your crap that comes from you, but this line stood out to me, in a fairly negative way. "with all my sniping".
Let me get this straight: you "snipe" (as you call it) at laserlights code, making invalid remarks about it and blaming his style on "++i". Yes, must be very confusing for a beginner. Especially since they are provably wrong. Now I reply, "sniping" at you, to tell you how wrong you were and that your code itself is buggy. This is very helpful for the beginner: he will learn not to use your advise - as it was wrong - and ignore your "sniping".
I passed your email around the office - it got a good laugh.
I don't have any problem with silverlight - because silverlight thinks positively. The re-written code was a bit short for me, but it was a positive move genuinely attempting to help with the original question.
Where is your contribution?
Never re-write code unless the user benefits
your post is the one that should be 'passed around the office'
I suggest you try googling "for loop C++ tutorial"
1. In every case the syntax i++ not ++i is used. It's not me who is out of touch. Teaching students the difference comes a lot later, and the for loop really isn't the best place to show it for the first time.
2. The questioner clearly wants to stop a n - as shown in the worked example.
3. Programming for errors is an essential coding habit. Wikibooks have an excellent tutorial on this - emphasing checks for division by zero, for example.
See C Programming/Error handling - Wikibooks, collection of open-content textbooks
4. Apart from silverlight I've yet to see anyone else put up code - it seems that criticising others needs a lot less effort.
Never re-write code unless the user benefits
I suggest you read Programming Principles and Practice by Bjarne Stroustrup (the creator of C++) and you will notice that he teaches to use ++i rather than i++. But hey, what does he know compared to you and your 6 staff?
I suggest you re-read what I said.
I said try googling - an independent source - not yours or mine. I did not hold up my team as the arbiters.
Never re-write code unless the user benefits
Well spotted. Should have been :
Did fyoung91 spot it?Code:val += (double) 1 / ( (double) ( 2*i - 1 ) );
Never re-write code unless the user benefits
Your style of casting for clarity is also arguably bad, since it opens up your code to some potential pitfalls. At the least, you should use the C++ casting operators to make your intention clear to the compiler.
If I did your homework for you, then you might pass your class without learning how to write a program like this. Then you might graduate and get your degree without learning how to write a program like this. You might become a professional programmer without knowing how to write a program like this. Someday you might work on a project with me without knowing how to write a program like this. Then I would have to do you serious bodily harm. - Jack Klein
