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Can someone explain loops to me?  RSS feed

 
Ryan Bishop
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Soooo...the one problem in my book is to create a loop where you add the integers from 1 to 50. I somehow did it correctly but honestly don't know
what it actually means. Can someone please explain what the parts in the loop mean or point me in the right direction?

 
Bhawana Gupta
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here you take i as counter which starts from 0 and counts up to max i.e. 50

every time loop executes for value of i (i.e. from 0 to 50), sum field is assigned its value added with i.
for example say at i = 0, sum = 0, then sum = 0 + 0 = 0;
again i = 1, sum = 0, then sum = 1 + 0 = 1;
and so on ....

Best way to know how your program works, is to use debugger....
 
Jesper de Jong
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See Oracle's tutorial: The for Statement
 
Paweł Baczyński
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Ryan Bishop wrote:Soooo...the one problem in my book is to create a loop where you add the integers from 1 to 50. I somehow did it correctly (...)



Well.. You did not do that correctly. You said you wanted to add integers from 1 to 50. And you added integers from 0 to 50. I know that mathematically this is the same...
But programatically it's incorrect. If you wanted multiplication instead of the sum you would get an incorrect value.
I'm not just nitpicking for no good reason. you should be careful with boundaries in loops as you might get yourself a serious and hard to spot bug.
 
Winston Gutkowski
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Ryan Bishop wrote:Can someone please explain what the parts in the loop mean or point me in the right direction?

Well, in logical terms, your for loop is precisely equivalent to the following:Not sure if it helps, but sometimes its good to see things written differently.

Bhawana Gupta wrote:Best way to know how your program works, is to use debugger...

Actually, I'm not sure that's true. IMO, the best way to know how your program works - especially when you're starting out - is to sit down with a paper and pencil and write it out.

HIH

Winston
 
fred rosenberger
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Better indentation might help...


This makes it easier to see what exactly is the loop and what isn't...Your loop consists of only lines 8-10. So focus on that, and ask specific questions if it doesn't make sense.
 
Robert D. Smith
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Winston Gutkowski wrote:
Ryan Bishop wrote:Can someone please explain what the parts in the loop mean or point me in the right direction?

Well, in logical terms, your for loop is precisely equivalent to the following:Not sure if it helps, but sometimes its good to see things written differently.

Bhawana Gupta wrote:Best way to know how your program works, is to use debugger...

Actually, I'm not sure that's true. IMO, the best way to know how your program works - especially when you're starting out - is to sit down with a paper and pencil and write it out.

HIH

Winston

The only difference between I would have written this than Winston is
.

And, for what it's worth, I second the pencil and paper. It's amazing how clear things become when you start thinking about *every* step you need to take to accomplish a task.

Regards,
Robert
 
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