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  • C++ - Need to learn some basics in a short while

    - by Rubys
    For reasons I will spare you, I have two weeks to learn some C++. I can learn alone just fine, but I need a good source. I don't think I have time to go through an entire book, and so I need some cliff notes, or possibly specific chapters/specialized resources I need to look up. I know my Asm/C/C# well, and so anything inherited from C, or any OOP is not needed. What I do need is some sources on the following subjects(I have a page that specifies what is needed, this is basically it, but I trimmed what I know): new/delete in C++ (as opposed to C#). Overloading cin/cout. Constructor, Destructor and MIL. Embedded Objects. References. Templates. If you feel some basic C++ concept that is not shared with C/C# is not included on this list, feel free to enter those as well. But the above subjects are the ones I'm supposed to roughly know in two week's time. Any help would be appreciated, thanks.

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  • django modeling

    - by SledgehammerPL
    Concept: Drinks are made of components. E.g. 10ml of Vodka. In some receipt the component is very particular (10ml of Finlandia Vodka), some not (10 ml of ANY Vodka). I wonder how to model a component to solve this problem - on stock I have particular product, which can satisfy more requirements. The model for now is: class Receipt(models.Model): name = models.CharField(max_length=128) (...) components = models.ManyToManyField(Product, through='ReceiptComponent') def __unicode__(self): return self.name class ReceiptComponent(models.Model): product = models.ForeignKey(Product) receipt = models.ForeignKey(Receipt) quantity = models.FloatField(max_length=9) unit = models.ForeignKey(Unit) class Admin: pass def __unicode__(self): return unicode(self.quantity!=0 and self.quantity or '') + ' ' + unicode(self.unit) + ' ' + self.product.genitive class Product(models.Model): name = models.CharField(max_length = 128) (...) class Admin: pass def __unicode__(self): return self.name class Stock(Store): products = models.ManyToManyField(Product) class Admin: pass def __unicode__(self): return self.name I think about making some table which joins real product (on stock) with abstract product (receiptcomponent). But maybe there's easy solution?

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  • Writing code to be a better programmer

    - by wtfsven
    A while back I heard on a podcast about a site listing "10 applications to write that will make you a better programmer." I'm desperate to find where this is, or at the very least a decent list from someone here. The thing is, I've been writing code for about 8 years now, and it's my passion. Very few things make me happier than getting lost in some C# or Python. But I've spent the last 2 years in a job that doesn't allow me much time to do what I love. Now everyone knows that the best way to keep your coding sword sharp is to use it, and I've noticed recently that mine is getting dull. Does anyone have any suggestions on some simple programs to help flex my coding muscle? I'm one of those odd few who actually likes writing CRUD applications, so stuff like that would be nice, too.

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  • Just 2 free months to learn or improve my skills

    - by microspino
    On the 30 of June I will leave my every day work to start as freelance developer. I'd like to set a period of 2 months apart to improve my dev skills. At work I code in C# and during my spare time I enjoyed building Ruby on Rails web applications and creating some Arduino prototypes. I'm something more than junior but I don't feel really a senior developer because I never had a big corporate project built and designed by me with help of other juniors (although I don't think this is really a good definiton of a "senior", It helps describing my feelings). Using a scale from 0 (ignorant) to 10 (proficient like a "samurai") the list below describes my skills that I would like to improve with just 2 months. I've already bought some nice and updated books on all the subjects hereunder: The order doesn't matter C = 1 C# & .Net = 6 Arduino & Processing = 2 Ruby = 5 Rails = 5 HTML/XHTML/CSS = 9 Javascript = 6 Objective-C/iPhone dev = 2 Python = 4 Django = 4 Desing Patterns = 3 Algorythms = 3 Git = 5 I haven't included SQL or Databases in general nor Networking because I spent 10 years working in the past with them and I feel pretty solid for now. As an aside, I've made up some interest in Redis, Node.js, HTML5 reading about them on the web. After two months, since I have to pay my bills, I could go searching for some new job. If learning and developing were really good maybe I could also invest on something I gave birth during them. Can You give me some piece of advice on which you think It's better to improve or develop a learning project on (something like a "summer of code" thing)? The all point Is to see my weaknesses and work on them.

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  • How to hash and check for equality of objects with circular references

    - by mfya
    I have a cyclic graph-like structure that is represented by Node objects. A Node is either a scalar value (leaf) or a list of n=1 Nodes (inner node). Because of the possible circular references, I cannot simply use a recursive HashCode() function, that combines the HashCode() of all child nodes: It would end up in an infinite recursion. While the HashCode() part seems at least to be doable by flagging and ignoring already visited nodes, I'm having some troubles to think of a working and efficient algorithm for Equals(). To my surprise I did not find any useful information about this, but I'm sure many smart people have thought about good ways to solve these problems...right? Example (python): A = [ 1, 2, None ]; A[2] = A B = [ 1, 2, None ]; B[2] = B A is equal to B, because it represents exactly the same graph. BTW. This question is not targeted to any specific language, but implementing hashCode() and equals() for the described Node object in Java would be a good practical example.

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  • Could this be considered a well-written PHP5 class?

    - by Ben Dauphinee
    I have been learning OOP principals on my own for a while, and taken a few cracks at writing classes. What I really need to know now is if I am actually using what I have learned correctly, or if I could improve as far as OOP is concerned. I have chopped a massive portion of code out of a class that I have been working on for a while now, and pasted it here. To all you skilled and knowledgeable programmers here I ask: Am I doing it wrong? class acl extends genericAPI{ // -- Copied from genericAPI class protected final function sanityCheck($what, $check, $vars){ switch($check){ case 'set': if(isset($vars[$what])){return(1);}else{return(0);} break; } } // --------------------------------- protected $db = null; protected $dataQuery = null; public function __construct(Zend_Db_Adapter_Abstract $db, $config = array()){ $this->db = $db; if(!empty($config)){$this->config = $config;} } protected function _buildQuery($selectType = null, $vars = array()){ // Removed switches for simplicity sake $this->dataQuery = $this->db->select( )->from( $this->config['table_users'], array('tf' => '(CASE WHEN count(*) > 0 THEN 1 ELSE 0 END)') )->where( $this->config['uidcol'] . ' = ?', $vars['uid'] ); } protected function _sanityRun_acl($sanitycheck, &$vars){ switch($sanitycheck){ case 'uid_set': if(!$this->sanityCheck('uid', 'set', $vars)){ throw new Exception(ERR_ACL_NOUID); } $vars['uid'] = settype($vars['uid'], 'integer'); break; } } private function user($action = null, $vars = array()){ switch($action){ case 'exists': $this->_sanityRun_acl('uid_set', $vars); $this->_buildQuery('user_exists_idcheck', $vars); return($this->db->fetchOne($this->dataQuery->__toString())); break; } } public function user_exists($uid){ return($this->user('exists', array('uid' => $uid))); } } $return = $acl_test->user_exists(1);

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  • Recursive CTE with alternating tables

    - by SOfanatic
    I've created a SQL fiddle here. Basically, I have 3 tables BaseTable, Files, and a LinkingTable. The Files table has 3 columns: PK, BaseTableId, RecursiveId (ChildId). What I want to do is find all the children given a BaseTableId (i.e., ParentId). The tricky part is that the way the children are found works like this: Take ParentId 1 and use that to look up a FileId in the Files table, then use that FileId to look for a ChildId in the LinkingTable, if that record exists then use the RecursiveId in the LinkingTable to look for the next FileId in the Files table and so on. This is my CTE so far: with CTE as ( select lt.FileId, lt.RecursiveId, 0 as [level], bt.BaseTableId from BaseTable bt join Files f on bt.BaseTableId = f.BaseTableId join LinkingTable lt on f.FileId = lt.FileId where bt.BaseTableId = @Id UNION ALL select rlt.FileId, rlt.RecursiveId, [level] + 1 as [level], CTE.BaseTableId from CTE --??? and this is where I get lost ... ) A correct output for BaseTableId = 1, should be: FileId|RecursiveId|level|BaseTableId 1 1 0 1 3 2 1 1 4 3 2 1

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  • How to Design Programs: An Introduction to Programming and Computing -- teacher guide access

    - by user295683
    Hello -- I'm a biologist switching careers, and trying to learn programming as a result. I stumbled upon the aforementioned book on Amazon, which jived with my liberal arts background. Despite my great satisfaction with the didactic approach, I was frustrated to see that the answers to the exercises are restricted to teachers only. As I am pursuing this endeavor on my own, this restriction dramatically cripples the value of this book. My request to the author's website for access to the answers has not been answered, and I would desperately like to continue with this book. Anyone have any experience dealing with the book's website, or at the very least a torrent of the answers? Otherwise, I suspect I will be relegated to using JavaScript for everything! Thanks!

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  • How to keep up the interest in job?

    - by stranger
    Hi, I have been working as Software Developer for 6+ yrs. And I have worked from start ups to big companies. I always feel some elements missing in me and those are interest, passion etc. In short, I don't feel motivated while coming to work. This makes me think how my work-life balance will look like once I reach at more responsible positions. I don't want to change my field and I feel blessed as well but I think I am not working passionately for my learning, future growth, improvement, skills etc. Any pointers will be highly appreciated. Thx

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  • Beginner questions regarding Python classes.

    - by Andy
    Hi. I am new to Python so please don't flame me if I ask something too noobish :) 1. Consider I have a class: class Test: def __init__(self, x, y): self.x = x self.y = y def wow(): print 5 * 5 Now I try to create an object of the class: x = Test(3, 4) This works as expected. However, when I try to call the method wow(), it returns an error, which is fixed by changing wow() to: def wow(self) Why do I need to include self and if I don't, what does the method mean?2. In the definition of __init__: def __init__(self, x, y): self.x = x self.y = y Why do I need to declare x and y, when I can do this: def __init__(self): self.x = x self.y = y I hope I am being clear... Thanks for your time.

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  • Very difficult SQL query

    - by db666
    For the following table definitions: Name Null? Type Comments ------------------------------- -------- ---- ------------------------------------ ENUM NOT NULL NUMBER(4) ENUM should not exceed a length of 4. ENAME CHAR(15) ADDRESS CHAR(25) ADDRESS should not exceed 25 characters. SALARY NUMBER(5) OFFICE CHAR(4) DNUM NOT NULL NUMBER(4) Department which this employee belongs to department Name Null? Type Comments ------------------------------- -------- ---- ------------------------------------- DNUM NOT NULL NUMBER(4) DMGR NOT NULL NUMBER(4) Department manager DNAME NOT NULL CHAR(15) project Name Null? Type Comments ------------------------------- -------- ---- ------------------------------------- PNUM NOT NULL NUMBER(4) PMGR NOT NULL NUMBER(4) Project manager PTITLE NOT NULL CHAR(15) emp_proj Name Null? Type ------------------------------- -------- ---- PNUM NOT NULL NUMBER(4) ENUM NOT NULL NUMBER(4) I have to write SQL query which will find the names of employees who do not share an office but work on the same project, and have different salaries... I've spent last three days trying to figure out something, but no idea as far. I will appreciate any advice.

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  • Is there any way to pass an anonymous array as an argument in C++?

    - by Jeremy Friesner
    Hi all, I'd like to be able to declare an array as a function argument in C++, as shown in the example code below (which doesn't compile). Is there any way to do this (other than declaring the array separately beforehand)? #include <stdio.h> static void PrintArray(int arrayLen, const int * array) { for (int i=0; i<arrayLen; i++) printf("%i -> %i\n", i, array[i]); } int main(int, char **) { PrintArray(5, {5,6,7,8,9} ); // doesn't compile return 0; }

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  • How can a language be interpreted by itself (like Rubinius)?

    - by japancheese
    I've been programming in Ruby for a while now with just the standard MRI implementation of Ruby, but I've always been curious about the other implementations I hear so much about. I was reading about Rubinius the other day, a Ruby interpreter written in Ruby. I tried looking it up in various places, but I was having a hard time figuring out exactly how something like this works. I've never had much experience in compilers or language writing but I'm really interested to figure it out. How exactly can a language be interpreted by itself? Is there a basic step in compiling that I don't understand where this makes sense? Can someone explain this to me like I'm an idiot (because that wouldn't be too far off base anyways)

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  • perl: added hash entry in a subroutine is lost

    - by hansi
    Why is the hash empty on the second call of printHash? my %hash = (); addToHash(\%hash); printHash(\%hash); sub addToHash { my %hash = %{$_[0]}; $hash{"test"} = "test"; printHash(\%hash); } sub printHash { print "printHash: \n"; my %hash = %{$_[0]}; foreach my $key (keys %hash) { print "key: $key, value: $hash{$key}\n"; } } Output: printHash: key: test, value: test printHash:

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  • .click() callback references local variable from the calling method instead of copying by value

    - by Eric Freese
    The following jQuery Javascript code is included on an otherwise empty page. $(function() { for (var i = 0; i < 10; i++) { element = $('<div>' + i + '</div>'); element.click(function() { alert(i); }); $('body').append(element); } }); The desired behavior is that this code should generate 10 div elements numbered from 0 to 9. When you click on a div element, an alert popup will show the number of the div element you clicked on (i.e. if a user clicks on the div element labeled '4', the alert popup should show the number 4). The alert popup instead shows the number 10 regardless of which div element is clicked on. How can I modify this code to make it behave in the desired way?

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  • Which programming paradigm or language open most your mind?

    - by Dom De Felice
    It is often said that some programming languages exist that once grasped can open your mind and change the way you write software. A sort of "software design enlightenment", we can say. I heard this about Lisp, Smalltalk, Haskell, pure functional programming in general.. What are your experiences about this? I know that the right language to use depends on your needs, but I would like to know the one that better improve your programming skills in general. What do you think would be the best language/paradigm to learn to end up being a better programmer in the long run?

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  • How do I build a python string from a raw (binary) ctype buffer?

    - by fcrazy
    I'm playing with Python and ctypes and I can't figure out how to resolve this problem. I call to a C function which fills a raw binary data. My code looks like this: class Client(): def __init__(self): self.__BUFSIZE = 1024*1024 self.__buf = ctypes.create_string_buffer(self.__BUFSIZE) self.client = ctypes.cdll.LoadLibrary(r"I:\bin\client.dll") def do_something(self): len_written = self.client.fill_raw_buffer(self.__buf, self.__BUFSIZE) my_string = repr(self.__buf.value) print my_string The problem is that I'm receiving binary data (with 0x00) and it's truncated when I tried to build my_string. How can I build my_string if self._buf contains null bytes 0x00? Any idea is welcome. Thanks

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  • How can I programmatically determine if my workstation is locked?

    - by AgentConundrum
    I'm writing up some productivity/metrics tools for myself to help monitor my focus throughout the day. Recently, I've noticed that I tend to get off track more than usual and feel the need to get up and go for walks/drinks/etc and I'm concerned that I'm "wasting" too much time. Since I always lock my computer when I go anywhere, and I unlock it as soon as I return (even if I'm just reading at my desk, etc), I was wondering how I can determine, in code, how long the machine is locked. I'm writing this in C# if that helps, but I'm open to other ideas. I like the windows service idea (and have accepted it) for simplicity and cleanliness, but unfortunately I don't think it will work for me in this particular case. I wanted to run this on my workstation at work rather than home (or in addition to home, I suppose), but it's locked down pretty hard courtesy of the DoD. That's part of the reason I'm rolling my own, actually. I'll write it up anyway and see if it works. Thanks everyone!

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  • Writing Strings to files in python

    - by Leif Andersen
    I'm getting the following error when trying to write a string to a file in pythion: Traceback (most recent call last): File "export_off.py", line 264, in execute save_off(self.properties.path, context) File "export_off.py", line 244, in save_off primary.write(file) File "export_off.py", line 181, in write variable.write(file) File "export_off.py", line 118, in write file.write(self.value) TypeError: must be bytes or buffer, not str I basically have a string class, which contains a string: class _off_str(object): __slots__ = 'value' def __init__(self, val=""): self.value=val def get_size(self): return SZ_SHORT def write(self,file): file.write(self.value) def __str__(self): return str(self.value) Furthermore, I'm calling that class like this: def write(self, file): for variable in self.variables: variable.write(file) I have no idea what is going on. I've seen other python programs writing strings to files, so why can't this one? Thank you very much for your help.

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  • Hardest concept to grasp as a beginner

    - by noizetoys
    When you were starting to program, what was the hardest concept for you to grasp? Was it recursion, pointers, linked lists, assignments, memory management? I was wondering what gave you headaches and how you overcame this issue and learned to love the bomb, I mean understand it. EDIT: As a followup, what helped you grok your hard-to-grasp concept?

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