Howdy. I am trying to understand programming and the book says to start by understanding pseudocode. I understood it in the first few chapters, but now stuff is getting pretty wacky.

An example problem would be...

"Find the sum of the squares of the integers from 1 to MySquare, where MySquare is input by the user."

So far I have come up with...



Declare sum as Interger

Declare MySquare as Interger

Repeat

Write "Enter an interger"

Input Mysquare


That is only less than half done. I am stuck about what to write after the user inputs MySquare.

Any help on this would be really appreciated. I really need an example of a completed version of this problem but the book offers none.

This is not for school, by the way. I am just trying to learn programming in my own time.

Pseudocode could be expressed in many ways as long as it's understandable. All you need to do is loop from 1 to the integer given by the user and inside the loop add the current square into the sum, 1+4+9+16+... Then you write out the resulting sum after you reach the end condition. I don't know how to respond to you by not giving you the whole answer..
In Basic I would start with something like this for the loop that does the actual work.
For i = 1 to MySquare
...
Next i

I don't mind if you want to give the answer. I got a ton of these problems to try and an example of a completed problem would really help.

What you said is pretty helpful in itself as well, but still pretty confusing. Programming svcks for those bad at math.

You need two variables and you already have those. Ok, one more for the index. You can use the variable i that I used in the loop. That's the index or just some integer to keep count of where we are going. Generally, you should use longer variable names, but this will do.

init
Sum can probably be assumed to be initialized to 0. And MySquare is what you get from the user.

loop
Then comes the loop above, and inside it you just add the values. sum = sum + i*i.

When the end condition is reached, you have the sum that was asked for and you can just write the value what's stored in variable sum.

Note that the Basic For construct means that the loop is run for each value from 1 to MySquare including the 1 and MySquare, and "Next i" adds 1 to i and moves execution back to the start of the loop. I don't know how they express pseudocode in your book. In Pascal style it could be something like
"for i from 1 to MySquare step 1", or
"while i <= MySquare"
They are just different ways of constructing the loop.

First you want to find MySquare. Since this is pseudo code, we can basically write what we want as long as we get the intention across:

MySquare <- getUserInput

Next we want to do http://rogercortesi.com/eqn/tempimagedir/eqn5301.png
(don't look if you haven't done sums in maths. If you have, it may help).

In english. For every number between 1 and MySquare, we need to square it and then add it to the sum.

So first we need to define the initial value of the sum, which will be 0.

Sum <- 0

Then for every number from 1 to MySquare, we square it and add it to the Sum:

From 1 to MySquare As k    Sum <-  Sum + k*k

Thanks for the help, guys. Now let me just soak in this informaton.

Honestly, this sounds like a pretty bad book at explaining how to learn to program IMO.

Your ability to solve problems is key to learning to program well. First step is understanding what the problem is asking. Write it out in natural language if you need to, then create a flow chart if you need to.

Once you've got a solid foundation in your ability to solve problems and think through all the little details, THEN you can go to actual real programming. I think you should at least look at some languages before doing pseudocode, as if you don't you won't have any idea how real languages behave. For example X < Y < Z makes perfect sense to you and me, but a computer doesn't read it like you and I do.

It may be trying to teach that, first what you do when you encounter a problem is write what you need to do without worrying to much about the implementation. The easiest way to do it might be pseudo code as a slightly more formatted version of English. IDK how the book explains pseudo code.

It could be that it wants something like this:

set MySquare to the user inputset sum to 0for the number k between 1 and MySquare    set sum to sum + k*k

In any case, functional programming makes much more sense imho. Why do we need the loop? The order doesn't matter. Ug. Imperative programming seems so ugly sometimes.

Great. Then the wannabe programmer not only has no idea whether what (s)he has written is computable or not, (s)he even has absolutely no idea that it's possible that what (s)he has written is not computable.

I didn't say it was a good method.

Anyway, most things are computable, unless you are asking silly questions like "Check if the program will terminate"

I dont like this stuff either, I wish it started me off at basic or something.

...or so it seems at first.

However, a program (an algorithm) which takes k∈? input values is basically a function f: ?^k → ?. For a fixed k there are ?₀^?₀k = 2^?₀ = ?? such functions. Only ?₀ of those are computable (which I'm too lazy to write a proof of at the moment), which leaves ?? non-computable functions. Conclusion: there are a lot more non-computable than computable functions.

Besides, http://en.wikipedia.org/wiki/List_of_undecidable_problems. (http://en.wikipedia.org/wiki/Post_correspondence_problem.)

I wouldn't try learning form that book. I learned from Beginning Programming for Dummies. Goes through many of the basics of programming with a bunch of different languages.

How many of those are going to come up in a beginners programming book? I have been programming for years and not yet met a problem that I couldn't compute.

(Although cool links)

Not many (probably none at all) but how can you know that the person learning to program won't attempt to do something non-computable in one of the exercises? Not all non-computable things are obviously non-computable and the terrible downside of pseudocode is that it's relatively easy to write something non-computable in it without even realising it, what with it being pseudocode which means you can basically write whatever the hell you want.

I can't argue. If I was to write a beginning programming book, I would chose a language close to pseudo code, like Python, and use that rather than pseudo code.

Lets just say the book doesn't do it as I would.

Hey. Thanks for the help so far, guys. It is starting to make more sense to me.

But I am still kind of confused what I should write after the user inputs the varible MySquare.

You've got two choices:

1) Initialise an integer variable to 0, then loop from 1 to MySquare adding the square of the current loop value to the variable, or

2) calculate (MySquare*(MySquare+1)*(2*MySquare+1))/6.


No doubt the second choice would be the way to go in any serious program where you needed the sum of the squares of the first MySquare integers because the complexity is constant (versus the linear complexity of the first approach) but I presume the point of the exercise is the first approach.

Just to give my opinion about pseudo-code.

I don't think that there is much danger in undecidable problems, but there is a very large downside when teaching beginners using pseudo-code: when writing pseudo-code one can never see code in action, and in my experience the greatest thing you can do to teach beginners is to show them why their programs don't work on concrete examples.