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  • Using a database class in my user class

    - by Josh
    In my project I have a database class that I use to handle all the MySQL stuff. It connects to a database, runs queries, catches errors and closes the connection. Now I need to create a members area on my site, and I was going to build a users class that would handle registration, logging in, password/username changes/resets and logging out. In this users class I need to use MySQL for obvious reasons... which is what my database class was made for. But I'm confused as to how I would use my database class in my users class. Would I want to create a new database object for my user class and then have it close whenever a method in that class is finished? Or do I somehow make a 'global' database class that can be used throughout my entire script (if this is the case I need help with that, no idea what to do there.) Thanks for any feedback you can give me.

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  • Using a datanase class in my user class?

    - by Josh
    In my project I have a database class that I use to handle all the MySQL stuff. It connects to a database, runs queries, catches errors and closes the connection. Now I need to create a members area on my site, and I was going to build a users class that would handle registration, logging in, password/username changes/resets and logging out. In this users class I need to use MySQL for obvious reasons... which is what my database class was made for. But I'm confused as to how I would use my database class in my users class. Would I want to create a new database object for my user class and then have it close whenever a method in that class is finished? Or do I somehow make a 'global' database class that can be used throughout my entire script (if this is the case I need help with that, no idea what to do there.) Thanks for any feedback you can give me.

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  • Can i access outer class objects in inner class

    - by Shantanu Gupta
    I have three classes like this. class A { public class innerB { //Do something } public class innerC { //trying to access objB here directly or indirectly over here. //I dont have to create an object of innerB, but to access the object created by A //i.e. innerB objInnerB = objB; //not like this innerB objInnerB= new innerB(); } public innerB objB{get;set;} } I want to access the object of class B in Class C that is created by class A. Is it possible somehow to make changes on object of Class A in Class C. Can i get Class A's object by creating event or anyhow.

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  • Linking a template class using another template class (error LNK2001)

    - by Luís Guilherme
    I implemented the "Strategy" design pattern using an Abstract template class, and two subclasses. Goes like this: template <class T> class Neighbourhood { public: virtual void alter(std::vector<T>& array, int i1, int i2) = 0; }; and template <class T> class Swap : public Neighbourhood<T> { public: virtual void alter(std::vector<T>& array, int i1, int i2); }; There's another subclass, just like this one, and alter is implemented in the cpp file. Ok, fine! Now I declare another method, in another class (including neighbourhood header file, of course), like this: void lSearch(/*parameters*/, Neighbourhood<LotSolutionInformation> nhood); It compiles fine and cleanly. When starting to link, I get the following error: 1>SolverFV.obj : error LNK2001: unresolved external symbol "public: virtual void __thiscall lsc::Neighbourhood<class LotSolutionInformation>::alter(class std::vector<class LotSolutionInformation,class std::allocator<class LotSolutionInformation> > &,int,int)" (?alter@?$Neighbourhood@VLotSolutionInformation@@@lsc@@UAEXAAV?$vector@VLotSolutionInformation@@V?$allocator@VLotSolutionInformation@@@std@@@std@@HH@Z)

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  • Building a database class in PHP

    - by Sprottenwels
    I wonder if I should write a database class for my application, and if so, how to accomplish it? Over there on SO, a guy mentioned it should be written as an abstract class. However, I can't understand why this would be a benefit. Do I understand correctly, that if I would write an abstract class, every other class that methods will need a database connection, could simply extend this abstract class and have it's own database object? If so, how is this different from a "normal" class where I could instantiate an database object? Another method would be to completely forget about my own class and to instantiate a mysqli object on demand. What do you recommend?

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  • Class design for calling "the same method" on different classes from one place

    - by betatester07
    Let me introduce my situation: I have Java EE application and in one package, I want to have classes which will act primarily as cache for some data from database, for example: class that will hold all articles for our website class that will hold all categories etc. Every class should have some update() method, which will update data for that class from database and also some other methods for data manipulation specific for that data type. Now, I would like to call update() method for all class instances (there will be exactly one class instance for every class) from one place. What is the best design?

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  • C#. Struct design. Why 16 byte is recommended size?

    - by maxima120
    I read Cwalina book (recommendations on development and design of .NET apps). He says that good designed struct has to be less than 16 bytes in size (for performance purpose). My questions is - why exactly is this? And (more important) can I have larger struct with same efficiency if I run my .NET 3.5 (soon to be .NET 4.0) 64-bit application on i7 under Win7 x64 (is this limitation CPU / OS based)? Just to stress again - I need as efficient struct as it is possible. I try to keep it in stack all the time, the application is heavily multi-threaded and runs on sub-millisecond intervals, the current size of the struct is 64 byte.

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  • How to easily substitute a Base class

    - by JTom
    Hi, I have the following hierarchy of classes class classOne { virtual void abstractMethod() = 0; }; class classTwo : public classOne { }; class classThree : public classTwo { }; All classOne, classTwo and classThree are abstract classes, and I have another class that is defining the pure virtual methods class classNonAbstract : public classThree { void abstractMethod(); // Couple of new methods void doIt(); void doItToo(); }; And right now I need it differently...I need it like class classNonAbstractOne : public classOne { void abstractMethod(); // Couple of new methods void doIt(); void doItToo(); }; class classNonAbstractTwo : public classTwo { void abstractMethod(); // Couple of new methods void doIt(); void doItToo(); }; and class classNonAbstractThree : public classThree { void abstractMethod(); // Couple of new methods void doIt(); void doItToo(); }; But all the nonAbstract classes have the same new methods, with the same code...and I would like to avoid copying all the methods and it's code to every nonAbstract class. How could I accomplish that? Hopefully it's understandable...

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  • c# pinvoke marshall struct

    - by Wouter Roux
    Hi, I have an unmanaged struct I'd like to marshal to c# that looks basically like this: struct DateTimeStruct{ double datetimestamp; }; struct MyStruct{ char firstname[40]; char lastname[40]; DateTimeStruct bday; unsigned integer bool1; int val1; }; What is the the correct c# declaration?

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  • struct.error: unpack requires a string argument of length 4

    - by Thomas O
    Python says I need 4 bytes for a format code of "BH": struct.error: unpack requires a string argument of length 4 Here is the code, I am putting in 3 bytes as I think is needed: major, minor = struct.unpack("BH", self.fp.read(3)) "B" = Unsigned char (1 byte) + "H" unsigned short (2 bytes) = 3 bytes (!?) struct.calcsize("BH") says 4 bytes.

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  • Using a class within a class?

    - by Josh
    I built myself a MySQL class which I use in all my projects. I'm about to start a project that is heavily based on user accounts and I plan on building my own class for this aswell. The thing is, a lot of the methods in the user class will be MySQL queries and methods from the MySQL class. For example, I have a method in my user class to update someone's password: class user() { function updatePassword($usrName, $newPass) { $con = mysql_connect('db_host', 'db_user', 'db_pass'); $sql = "UPDATE users SET password = '$newPass' WHERE username = '$userName'"; $res = mysql_query($sql, $con); if($res) return true; mysql_close($con); } } (I kind of rushed this so excuse any syntax errors :) ) As you can see that would use MySQL to update a users password, but without using my MySQL class, is this correct? I see no way in which I can use my MySQL class within my users class without it seeming dirty. Do I just use it the normal way like $DB = new DB();? That would mean including my mysql.class.php somewhere too... I'm quite confused about this, so any help would be appreciated, thanks.

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  • Identifying that a variable is a new-style class in Python?

    - by Dave Johansen
    I'm using Python 2.x and I'm wondering if there's a way to tell if a variable is a new-style class? I know that if it's an old-style class that I can do the following to find out. import types class oldclass: pass def test(): o = oldclass() if type(o) is types.InstanceType: print 'Is old-style' else: print 'Is NOT old-style' But I haven't been able to find anything that works for new-style classes. I found this question, but the proposed solutions don't seem to work as expected, because simple values as are identified as classes. import inspect def newclass(object): pass def test(): n = newclass() if inspect.isclass(n): print 'Is class' else: print 'Is NOT class' if inspect.isclass(type(n)): print 'Is class' else: print 'Is NOT class' if inspect.isclass(type(1)): print 'Is class' else: print 'Is NOT class' if isinstance(n, object): print 'Is class' else: print 'Is NOT class' if isinstance(1, object): print 'Is class' else: print 'Is NOT class' So is there anyway to do something like this? Or is everything in Python just a class and there's no way to get around that?

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  • How to get a Class literal from a generically specific Class

    - by h2g2java
    There are methods like these which require Class literals as argument. Collection<EmpInfo> emps = SomeSqlUtil.select( EmpInfo.class, "select * from emps"); or GWT.create(Razmataz.class); The problem presents itself when I need to supply generic specific classes like EmpInfo<String> Razmataz<Integer> The following would be wrong syntax Collection<EmpInfo<String>> emps = SomeSqlUtil.select( EmpInfo<String>.class, "select * from emps"); or GWT.create(Razmataz<Integer>.class); Because you cannot do syntax like Razmataz<Integer>.class So, how would I be able to squeeze a class literal out of EmpInfo<String> Razmataz<Integer> so that I could feed them as arguments to methods requiring Class literals? Further info Okay, I confess that I am asking this primarily for GWT. I have a pair of GWT RPC interface Razmataz. (FYI, GWT RPC interface has to be defined in server-client pairs). I plan to use the same interface pair for communicating whether it be String, Integer, Boolean, etc. GWT.create(Razmataz) for Razmataz<T> complains that, since I did not specify T, GWT compiler treated it as Object. Then GWT compiler would not accept Object class. It needs to be more specific than being an Object. So, it seems there is no way for me to tell GWT.create what T is because a Class literal is a runtime concept while generics is a compile time concept, Right?

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  • C++ struct containing unsigned char and int bug

    - by powerfear
    Ok i have a struct in my C++ program that is like this: struct thestruct { unsigned char var1; unsigned char var2; unsigned char var3[2]; unsigned char var4; unsigned char var5[8]; int var6; unsigned char var7[4]; }; When i use this struct, 3 random bytes get added before the "var6", if i delete "var5" it's still before "var6" so i know it's always before the "var6". But if i remove the "var6" then the 3 extra bytes are gone. If i only use a struct with a int in it, there is no extra bytes. So there seem to be a conflict between the unsigned char and the int, how can i fix that?

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  • Modify existing struct alignment in Visual C++

    - by Crend King
    Is there a way to modify the member alignment of an existing struct in Visual C++? Here is the background: I use an 3rd-party library, which uses several structs. To fill up the structs, I pass the address of the struct instance to some functions. Unfortunately, the functions only returns unaligned buffer, so that data of some members are always wrong. /Zp is out of choice, since it breaks the other parts of the program. I know #pragma pack modifies the alignment of the following struct, but I do not want to copy the structs into my code, for the definitions in the library might change in the future. Sample code: test.h: struct am_aligned { BYTE data1[10]; ULONG data2; }; test.cpp: include "test.h" // typedef alignment(1) struct am_aligned am_unaligned int APIENTRY wWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPTSTR lpCmdLine, int nCmdShow) { char buffer[20] = {}; for (int i = 0; i < sizeof(unaligned_struct); i++) { buffer[i] = i; } am_aligned instance = *(am_aligned*) buffer; return 0; } instance.data2 is 0x0f0e0d0c, while 0x0d0c0b0a is desired. The commented line does not work of course. Thanks for help!

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  • Getting the class of an n dimensional array of an runtime supplied class name

    - by MeBigFatGuy
    Given a fully qualified class name, and a number of dimensions, i would like to get the Class name for this class. I believe i can do this like such public Class<?> getArrayClass(String className, int dimensions) throws ClassNotFoundException { Class<?> elementType = Class.forName(className); return Array.newInstance(elementType, new int[dimensions]).getClass(); } However this requires me to create an unneeded instance of the class. Is there a way to do this without creating the instance? It does not appear that Class.forName("[[[[Ljava/lang/String;") (or a algorithmically generated version) works correctly in all instances from various blog posts i've seen.

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  • struct size is different from typedef version?

    - by samoz
    I have the following struct declaration and typedef in my code: struct blockHeaderStruct { bool allocated; unsigned int length; }; typedef struct blockHeaderStruct blockHeader; When I do sizeof(blockheader), I get the value of 4 bytes back, but when I do sizeof(blockHeaderStruct), I get 8 bytes. Why is this happening? Why am I not getting 5 back instead?

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  • C++: why a self pointer of a struct automatically changes to void*

    - by Stone
    struct ptr{ int node; ptr *next; ptr(){} ptr(int _node, ptr *_next){ node=_node; next=_next; } }; struct list_t{ ptr *sht; int size; void push(int node){ size++; sht=new ptr(node,sht); } }shthead[100001], comp[200001], tree[200001]; The struct ptr is a smart pointer, be used as a linked list. But when I debug the code in gdb, I found that the ptr*'s were all converted to void*. GDB output: (gdb) pt ptr type = struct ptr { int node; void *next; public: ptr(void); ptr(int, void *); } However, I can still see the data of the struct if I covert them back to ptr* in gdb. What's the reason for this please?

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  • Returning and instance of a Class given its .class (MyClass.class)

    - by jax
    I have an enum that will hold my algorithms. I cannot instantiate these classes because I need the application context which is only available once the application has started. I want to load the class at runtime when I choose by calling getAlgorithm(Context cnx). How do I easily instantiate a class at runtime given its .class (and my constructor takes arguments)? All my classes are subclasses of Algorithm. public enum AlgorithmTypes { ALL_FROM_9_AND_LAST_FROM_10_ID(AlgorithmFactory.AlgorithmAllFrom9AndLastFrom10Impl.class), ALL_FROM_9_AND_LAST_FROM_10_CURRENCY_ID(AlgorithmFactory.AlgorithmAllFrom9AndLastFrom10Impl.class), DIVIDE_BY_9_LESS_THAN_100(AlgorithmFactory.AlgorithmAllFrom9AndLastFrom10Impl.class), TABLES_BEYOND_5_BY_5(AlgorithmFactory.AlgorithmAllFrom9AndLastFrom10Impl.class); private Class<? extends Algorithm> algorithm; AlgorithmTypes(Class<? extends Algorithm> c) { algorithm = c; } public Algorithm getAlgorithm(Context cnx) { return //needs to return the current algoriths constructor which takes the Context Algorithm(Context cnx); } }

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  • Regarding C typedef struct

    - by Bruce Duncan
    I have multiple instances of typedef struct box so box box1, box box2 etc. The members of the struct are length, width, height etc. typedef struct { int width; int height; } box; box box1; box box2; How can I create a function that operates on all the width members of each box instance? My confusion is how do I pass a pointer to a typedef struct member that works across all instances of box. I know how to pass a pointer to a specific instance member like box1.width but how to pass .width and then do box1.width=value; box2.width=value; box3.width=value; within the function?

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  • How to add class to selective <li> in a generated menu

    - by Vikram
    Hi I am looking for a solution to add a class to every list item <li> which has a child item with a class of <span class="separator"> and a different class to <li> with an anchor link. I use Joomla and the menu is being generated somewhat like this: <ul class="menu"> <li class="item1"><a href="<!-- link goes here -->"><span>Home</span></a></li> <li class="parent item59"><span class="separator"><span>Demo</span></span></li> <li class="item62"><a href="<!-- link goes here -->"><span>Article</span></a></li> <li id="current" class="parent active item27"><a href="<!-- link goes here -->"><span>CMS</span></a> <ul> <li class="item50"><a href="<!-- link goes here -->"><span>The News</span></a></li> <li class="item48"><a href="<!-- link goes here -->"><span>Web Links</span></a></li> <li class="item65"><span class="separator"><span /></span></li> <li class="item49"><a href="<!-- link goes here -->"><span>News Feeds</span></a></li> <li class="item66"><span class="separator"><span /></span></li> <li class="item67"><span class="separator"><span /></span></li> <li class="item68"><span class="separator"><span /></span></li> </ul> </li> <li class="item71"><span class="separator"><span>Help</span></span></li> </ul> What I want is to add class "anclink" or "seplink" to the <li> depending on their child item so that the final output looks like below. <ul class="menu"> <li class="item1 anclink"><a href="<!-- link goes here -->"><span>Home</span></a></li> <li class="parent item59 seplink"><span class="separator"><span>Demo</span></span></li> <li class="item62 anclink"><a href="<!-- link goes here -->"><span>Article</span></a></li> <li id="current" class="parent active item27" anclink><a href="<!-- link goes here -->"><span>CMS</span></a> <ul> <li class="item50 anclink"><a href="<!-- link goes here -->"><span>The News</span></a></li> <li class="item48 anclink"><a href="<!-- link goes here -->"><span>Web Links</span></a></li> <li class="item65 seplink"><span class="separator"><span /></span></li> <li class="item49 anclink"><a href="<!-- link goes here -->"><span>News Feeds</span></a></li> <li class="item66 seplink"><span class="separator"><span /></span></li> <li class="item67 seplink"><span class="separator"><span /></span></li> <li class="item68 seplink"><span class="separator"><span /></span></li> </ul> </li> <li class="item71 seplink"><span class="separator"><span>Help</span></span></li> </ul> How can I achieve this using PHP or even a jQuery solution will be fine. Kindly help.

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  • Database Server Hardware components (order of importance), CPU speed VS CPU cache vs RAM vs DISK

    - by nulltorpedo
    I am new to database world and would like to know what are crucial hardware specs when it comes to database performance. I have searched the internet and found this so far (In order of decreasing importance): 1) Hard Disk: Get an SSD basically (much more IOPS than spinners) 2) Memory: Get as much as you can afford 3) CPU: For the same $ spent, prefer larger cache size over speed. Are these findings sensible? EDIT: I would like to focus on CPU speed VS CPU cache size. EDIT2: The database is used to store some combination of ints and int arrays with few text fields. There are a lot of Select queries looking for existing entries. If entry is not found, then insert it. I would say most of processing would be trying to find a match across a table with 200 columns and 20k rows. The insert statements are very few. EDIT3: Also, we have a lot of views (basically select queries).

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