The Big Programming Thread - Page 835

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1. This is not a "do my homework for me" thread. If you have specific questions, ask, but don't post an assignment or homework problem and expect an exact solution.
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3. If you can't articulate why a language is bad, don't start slinging shit about it. Just remember that nothing is worse than making CSS IE6 compatible.
4. Use [code] tags to format code blocks.

Askelad

France20 Posts

February 05 2017 03:58 GMT

#16681

TheEmulator

28100 Posts

February 05 2017 04:30 GMT

#16682

Yea Matlab isn't too difficult to understand. I'm sure there's shitloads of materials on the internet to learn from as well. I never had to use it in Linear Algebra, although I used it a bit in Econometrics and I'm pretty sure we learned most of what was needed after a couple of tutorial lectures.

maybenexttime

Poland5817 Posts

February 05 2017 08:19 GMT

#16683

MATLAB question.

I am learning how to create a simple dialog box GUI in Matlab, and I am not sure what is the proper way to handle invalid inputs. Namely, the pattern repeats itself: I have the parameter name, default value variable name, condition, and the error message.

Should I create a function that uses this pattern or leave it as it is now? Is it more proper to have explicit if statements or to reduce the number of lines considerably by making the if statements implicit (hidden in a dedicated function).

+ Show Spoiler +

while open_prompt
    open_prompt = false;
    
    answer_initial = inputdlg(prompt_initial, name_initial, num_lines, ...
        default_initial);
    default_initial{1} = answer_initial{1};
    
    if (str2double(answer_initial{2}) >= 0) & ...
            (str2double(answer_initial{2}) <= str2double(answer_initial{1}))
        
        default_initial{2} = answer_initial{2};
    else
        uiwait(errordlg('Support A location outside of the beam length'));
        default_initial{2} = '';
        open_prompt = true;
    end
    
    if (str2double(answer_initial{3}) >= 0) & ...
            (str2double(answer_initial{3}) <= str2double(answer_initial{1}))
        
        default_initial{3} = answer_initial{3};
    else
        uiwait(errordlg('Support B location outside of the beam length'));
        default_initial{3} = '';
        open_prompt = true;
    end
    
    if (str2double(answer_initial{4}) >= 0)
        
        default_initial{4} = answer_initial{4};
    else
        uiwait(errordlg('Number of distributed loads cannot be negative'));
        default_initial{4} = '';
        open_prompt = true;
    end
    
    if (str2double(answer_initial{5}) >= 0)
        
        default_initial{5} = answer_initial{5};
    else
        uiwait(errordlg('Number of point loads cannot be negative'));
        default_initial{5} = '';
        open_prompt = true;
    end
    
    if (str2double(answer_initial{6}) >= 0)
        
        default_initial{6} = answer_initial{6};
    else
        uiwait(errordlg('Number of point moments cannot be negative'));
        default_initial{6} = '';
        open_prompt = true;
    end
end

Blisse

Canada3710 Posts

February 05 2017 08:38 GMT

#16684

IMO this would be a better pattern


while loop
    
    loop = false
    data = get_input

    if !cond
        show_error
        loop = true
    
    if !cond
        show_error
        loop = true

    ...
    
    if !loop 
        action

In which case no need to make a function

maybenexttime

Poland5817 Posts

February 05 2017 09:54 GMT

#16685

On February 05 2017 17:38 Blisse wrote:
IMO this would be a better pattern


while loop
    
    loop = false
    data = get_input

    if !cond
        show_error
        loop = true
    
    if !cond
        show_error
        loop = true

    ...
    
    if !loop 
        action

In which case no need to make a function

Thanks for your input. I am, however, not sure this is going to maintain the same functionality. In my code the dialog box has a set of default values: default_initial = {'10', '0', '10', '1', '1', '1'}. By checking the validity of each input value individually, I can either replace the default value with the valid input value (default_initial{2} = answer_initial{2}) or make the field empty (default_initial{2} = '').

    if (str2double(answer_initial{2}) >= 0) & ...
            (str2double(answer_initial{2}) <= str2double(answer_initial{1}))
        
        default_initial{2} = answer_initial{2};
    else
        uiwait(errordlg('Support A location outside of the beam length'));
        default_initial{2} = '';
        open_prompt = true;
    end

If I were to put all actions in the very last if statement, then upon opening the dialog box again (in the next iteration of the while loop) the initial default values would be used, and all valid inputs would be lost.

Shield

Bulgaria4824 Posts

February 05 2017 13:15 GMT

#16686

On February 05 2017 12:58 Askelad wrote:

Show nested quote +

Makes even less sense. Seriously what was that rant about the irrationals...

Educate yourself: https://en.wikipedia.org/wiki/Irrational_number

On February 05 2017 12:17 travis wrote:
since it (understandably) turned into a semantics argument, I'll let everyone know that I selected all of the options and got the answer correct.

It doesn't seem the best answer to me. Real numbers should be better because others do not mention irrational numbers. Or did you select real numbers too?

Nesserev

Belgium2760 Posts

February 05 2017 13:57 GMT

#16687

--- Nuked ---

Shield

Bulgaria4824 Posts

February 05 2017 14:04 GMT

#16688

On February 05 2017 22:57 Nesserev wrote:

Show nested quote +

Uh, lol what? That's kind of uncalled for, especially because it's clear that you're in the wrong here. Sorry, but the one that needs a lesson is you... a lesson in not being an idiot, and perhaps set theory.

You should focus on this: "for all x in D[there exists a y in D ( x < y)]"

That statement is true for any number set Travis listed. If D is either the set of integers, natural numbers or rational numbers, there's zero reason to consider irrational numbers, because irrational numbers aren't in those sets...

How can 'true' be more correct than 'true'?

So, where is your confusion coming from? All that I can think of is that you didn't parse the question correctly, and think D is supposed to be any random interval of real numbers? And you seem to be reinforcing this idea because you're grasping back at irrational numbers...

Dude, you're wrong and you need to be taught how not to be an idiot. Or go study some math?

Integers: true (for all x in D[there exists a y in D ( x < y)])
Rational numbers: true (for all x in D[there exists a y in D ( x < y)])
Natural numbers: true (for all x in D[there exists a y in D ( x < y)])

Set of real numbers has integers, rational numbers and natural numbers. So, all of above is true. Plus, irrational numbers which are in the set of real numbers. E.g.
x = √2
y = √3
x < y

The set of real numbers is BIGGER than the union of natural numbers, integers and rationals.

spinesheath

Germany8679 Posts

February 05 2017 14:59 GMT

#16689

For the record: The question asks for which set a condition holds, not which set among the list is the best match or anything like that. So you have to evaluate each set by itself. As per the wording of the question, the answer is "it is true for all 4 sets".

Shield

Bulgaria4824 Posts

February 05 2017 15:02 GMT

#16690

On February 05 2017 23:59 spinesheath wrote:
For the record: The question asks for which set a condition holds, not which set among the list is the best match or anything like that. So you have to evaluate each set by itself. As per the wording of the question, the answer is "it is true for all 4 sets". Nobody is doubting that integers are part of the real numbers, it just has nothing to do with the question.

Sure, I was asking travis if he chose all 4 but some people can't argue in a respectful way.

On February 05 2017 12:58 Askelad wrote:

Show nested quote +

Makes even less sense. Seriously what was that rant about the irrationals...

Hanh

146 Posts

February 05 2017 15:04 GMT

#16691

The question is not about which set include more numbers that fulfill the condition but which ones do or not. This isn't answering the question (and arguably showing off).

Deleted User 3420

24492 Posts

February 05 2017 15:36 GMT

#16692

I encrypted my vim file

how do I remove the encryption from within vim

I don't want it to be encrypted anymore

ok I figured it out

:set key=

vim is weird though.. I had to exit with :wq and not :x or it wasn't saving the change.. no idea why. wtf tbh

Wrath

3174 Posts

February 05 2017 15:47 GMT

#16693

On February 06 2017 00:36 travis wrote:
I encrypted my vim file

how do I remove the encryption from within vim

I don't want it to be encrypted anymore

ok I figured it out

:set key=

vim is weird though.. I had to exit with :wq and not :x or it wasn't saving the change.. no idea why. wtf tbh

Wasn't always :wq to save and :q! to exit without saving? Never heard of :x before.

Hanh

146 Posts

February 05 2017 16:29 GMT

#16694

:x won't save if there are no changes. Maybe removing encryption isn't considered a change? Vim is weird.

Deleted User 3420

24492 Posts

February 05 2017 20:32 GMT

#16695

WHAT IS GOING ON

why does this:


  if(shape_choice == 2) {
    scanf("%c ", &char_choice);
    printf("%c", char_choice);
    printf("Enter character and size: ");

simply print an empty line and then ask me for a character and size
it doesn't even give me a chance to input a character the first time

whelp, figured it out
any time you have a scanf you're gonna need a whitespace before your next scanf? that's so annoying

Shield

Bulgaria4824 Posts

February 05 2017 21:52 GMT

#16696

Welcome to C where you can f*ck yourself nicely.

Not that C++ is perfect, but it's much safer.

You might want to read this answer because your whitespace should be first: http://stackoverflow.com/a/13543113

Blisse

Canada3710 Posts

February 05 2017 22:56 GMT

#16697

On February 05 2017 18:54 maybenexttime wrote:

Show nested quote +

On February 05 2017 17:38 Blisse wrote:
IMO this would be a better pattern


while loop
    
    loop = false
    data = get_input

    if !cond
        show_error
        loop = true
    
    if !cond
        show_error
        loop = true

    ...
    
    if !loop 
        action

In which case no need to make a function

    if (str2double(answer_initial{2}) >= 0) & ...
            (str2double(answer_initial{2}) <= str2double(answer_initial{1}))
        
        default_initial{2} = answer_initial{2};
    else
        uiwait(errordlg('Support A location outside of the beam length'));
        default_initial{2} = '';
        open_prompt = true;
    end

Not totally certain I'm walking through your logic and explanation in the same way, but there is no next iteration of the loop if you've put all the action in the else block - the loop exits.

The `action` in my example would be doing whatever you needed with the answer_initial (in this case copying each value to default_initial).

edit: ohh okay I see what you mean by losing all the valid values on the next iteration, when the user enters valid and invalid values you want to keep the valid values and not set the invalid ones. Let me think about that..

edit2: i think your way is fine if you have that requirement. in that case i think it'd be nice to make a function. generally i disagree with making extra functions "for readability" if that function is only used once. the exception would be in cases where you'd expect that function to exist, i.e. client::isConnected(). in this case i'd like a somewhat generic function like `bool setArrayValueIfTrue(arr, index, value, cond)`.

maybenexttime

Poland5817 Posts

February 06 2017 09:18 GMT

#16698

On February 06 2017 07:56 Blisse wrote:
+ Show Spoiler +

On February 05 2017 18:54 maybenexttime wrote:

Show nested quote +

On February 05 2017 17:38 Blisse wrote:
IMO this would be a better pattern


while loop
    
    loop = false
    data = get_input

    if !cond
        show_error
        loop = true
    
    if !cond
        show_error
        loop = true

    ...
    
    if !loop 
        action

In which case no need to make a function

    if (str2double(answer_initial{2}) >= 0) & ...
            (str2double(answer_initial{2}) <= str2double(answer_initial{1}))
        
        default_initial{2} = answer_initial{2};
    else
        uiwait(errordlg('Support A location outside of the beam length'));
        default_initial{2} = '';
        open_prompt = true;
    end

Thank you! I might have a few more questions regarding putting such recurring patterns into functions, but I'll give it a try myself first.

Silvanel

Poland4756 Posts

February 06 2017 09:31 GMT

#16699

So our customer just recently acccepted the software. Its a great feeling that work You (and few hundred other people) have been doing for last year and a half did not go in vain. Will be deployed to market in next 1-2 months.

I know this post isnt very productive. I just wanted to share my excitement.

AKnopf

Germany259 Posts

February 06 2017 09:45 GMT

#16700

On February 06 2017 18:31 Silvanel wrote:
So our customer just recently acccepted the software. Its a great feeling that work You (and few hundred other people) have been doing for last year and a half did not go in vain. Will be deployed to market in next 1-2 months.

I know this post isnt very productive. I just wanted to share my excitement.

Sharing positive feelings should never be considered unproductive. :-)

Congrats! It's always such a nice feeling to have your work published, even if it's only a small fix or a simple feature the customer needs. A satisfied customer is almost as good as the feeling when jenkins works and your latest commit doesn't break the test suite. ;-D

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