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  • Changing type of object in a conditional

    - by David Doria
    I'm having a bit of trouble with dynamic_casting. I need to determine at runtime the type of an object. Here is a demo: include include class PersonClass { public: std::string Name; virtual void test(){}; //it is annoying that this has to be here... }; class LawyerClass : public PersonClass { public: void GoToCourt(){}; }; class DoctorClass : public PersonClass { public: void GoToSurgery(){}; }; int main(int argc, char *argv[]) { PersonClass* person = new PersonClass; if(true) { person = dynamic_cast(person); } else { person = dynamic_cast(person); } person-GoToCourt(); return 0; } I would like to do the above. The only legal way I found to do it is to define all of the objects before hand: PersonClass* person = new PersonClass; LawyerClass* lawyer; DoctorClass* doctor; if(true) { lawyer = dynamic_cast(person); } else { doctor = dynamic_cast(person); } if(true) { lawyer-GoToCourt(); } The main problem with this (besides having to define a bunch of objects that won't be use) is that I have to change the name of the 'person' variable. Is there a better way? (I am not allowed to change any of the classes (Person, Lawyer, or Doctor) because they are part of a library that people who will use my code have and won't want to change). Thanks, Dave

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  • Global name not defined error in Django/Python trying to set foreignkey

    - by Mark
    Summary: I define a method createPage within a file called PageTree.py that takes a Source model object and a string. The method tries to generate a Page model object. It tries to set the Page model object's foreignkey to refer to the Source model object which was passed in. This throws a NameError exception! I'm trying to represent a website which is structured like a tree. I define the Django models Page and Source, Page representing a node on the tree and Source representing the contents of the page. (You can probably skip over these, this is a basic tree implementation using doubly linked nodes). class Page(models.Model): name = models.CharField(max_length=50) parent = models.ForeignKey("self", related_name="children", null=True); firstChild = models.ForeignKey("self", related_name="origin", null=True); nextSibling = models.ForeignKey("self", related_name="prevSibling", null=True); previousSibling = models.ForeignKey("self", related_name="nxtSibling", null=True); source = models.ForeignKey("Source"); class Source(models.Model): #A source that is non dynamic will be refered to as a static source #Dynamic sources contain locations that are names of functions #Static sources contain locations that are places on disk name = models.CharField(primary_key=True, max_length=50) isDynamic = models.BooleanField() location = models.CharField(max_length=100); I've coded a python program called PageTree.py which allows me to request nodes from the database and manipulate the structure of the tree. Here is the trouble making method: def createPage(pageSource, pageName): page = Page() page.source = pageSource page.name = pageName page.save() return page I'm running this program in a shell through manage.py in Windows 7 manage.py shell from mysite.PageManager.models import Page, Source from mysite.PageManager.PageTree import * ... create someSource = Source(), populate the fields, and save it ... createPage(someSource, "test") ... NameError: global name 'source' is not defined When I type in the function definition for createPage into the shell by hand, the call works without error. This is driving me bonkers and help is appreciated.

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  • How can I overlay a watermark on an already resampled image in PHP (using GD) ?

    - by Rick
    Here's my current code: define('IMG_WIDTH', (isset ($_GET['width'])) ? (int) $_GET['width'] : 99); define('IMG_HEIGHT', (isset ($_GET['height'])) ? (int) $_GET['height'] : 75); $image = imagecreatefromjpeg($_GET['image']); $origWidth = imagesx($image); $origHeight = imagesy($image); $croppedThumb = imagecreatetruecolor(IMG_WIDTH, IMG_HEIGHT); if ($origWidth > $origHeight) { $leftOffset = ($origWidth - $origHeight) / 2; imagecopyresampled($croppedThumb, $image, 0, 0, $leftOffset, 0, IMG_WIDTH, IMG_HEIGHT, $origHeight, $origHeight); } else { $topOffset = ($origHeight - $origWidth) / 2; imagecopyresampled($croppedThumb, $image, 0, 0, 0, $topOffset, IMG_WIDTH, IMG_HEIGHT, $origWidth, $origWidth); } It basically takes an image and re-sizes it to create a thumbnail. It works quite nicely. What I would like to do now is add a watermark to the bottom right corner. I've seen the imagecopymerge function used for this... However, that doesn't seem to allow me to supply a resampled image as the source. How can I take my already modified image and add a watermark? :/ I've thought of saving the image to /tmp and then unlink()'ing it once I've added the watermark but that seems like a bit of a mess...

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  • How am i overriding this C++ inherited member function without the virtual keyword being used?

    - by Gary Willoughby
    I have a small program to demonstrate simple inheritance. I am defining a Dog class which is derived from Mammal. Both classes share a simple member function called ToString(). How is Dog overriding the implementation in the Mammal class, when i'm not using the virtual keyword? (Do i even need to use the virtual keyword to override member functions?) mammal.h #ifndef MAMMAL_H_INCLUDED #define MAMMAL_H_INCLUDED #include <string> class Mammal { public: std::string ToString(); }; #endif // MAMMAL_H_INCLUDED mammal.cpp #include <string> #include "mammal.h" std::string Mammal::ToString() { return "I am a Mammal!"; } dog.h #ifndef DOG_H_INCLUDED #define DOG_H_INCLUDED #include <string> #include "mammal.h" class Dog : public Mammal { public: std::string ToString(); }; #endif // DOG_H_INCLUDED dog.cpp #include <string> #include "dog.h" std::string Dog::ToString() { return "I am a Dog!"; } main.cpp #include <iostream> #include "dog.h" using namespace std; int main() { Dog d; std::cout << d.ToString() << std::endl; return 0; } output I am a Dog! I'm using MingW on Windows via Code::Blocks.

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  • Why I'm not getting "Multiple definition" error from the g++?

    - by ban
    I tried to link my executable program with 2 static libraries using g++. The 2 static libraries have the same function name. I'm expecting a "multiple definition" linking error from the linker, but I did not received. Can anyone help to explain why is this so? staticLibA.h #ifndef _STATIC_LIBA_HEADER #define _STATIC_LIBA_HEADER int hello(void); #endif staticLibA.cpp #include "staticLibA.h" int hello(void) { printf("\nI'm in staticLibA\n"); return 0; } output: g++ -c -Wall -fPIC -m32 -o staticLibA.o staticLibA.cpp ar -cvq ../libstaticLibA.a staticLibA.o a - staticLibA.o staticLibB.h #ifndef _STATIC_LIBB_HEADER #define _STATIC_LIBB_HEADER int hello(void); #endif staticLibB.cpp #include "staticLibB.h" int hello(void) { printf("\nI'm in staticLibB\n"); return 0; } output: g++ -c -Wall -fPIC -m32 -o staticLibB.o staticLibB.cpp ar -cvq ../libstaticLibB.a staticLibB.o a - staticLibB.o main.cpp extern int hello(void); int main(void) { hello(); return 0; } output: g++ -c -o main.o main.cpp g++ -o multipleLibsTest main.o -L. -lstaticLibA -lstaticLibB -lstaticLibC -ldl -lpthread -lrt

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  • How to convert a rectangle to TRBL CSS rect value?

    - by VLostBoy
    I'm not quite sure how to put this, but here goes... The css clip attribute is defined like so: rect(top, right, bottom, left). However, I'm exploring the use of a custom Rectangle 'class' to encapsulate some operations. The rectangle class has the attributes height, width and x, y. The x and y values are encapsulated in a Point object, and the height and width are encapsulated in a Dimension object, the rectangle being a composite of a point (its top-left location) and a dimension (width and height). So far so good. I though it would be pretty simple on the basis of having the rectangles x, y, width and height values to define the css rect attribute in terms of top, right, bottom, left, but I've become hopelessly confused- I've been googling for a while, and I can't seem to find any documentation as to what the TRBL values actually are or what they represent. For example, should I be thinking in terms of co-ordinates, in which case, surely I can describe the rectangle as a css rect using the rectangles x position for Top, x position + width for Right, the rectangles height + y for Bottom and its y position for Left... but thats a load of BS, surely? Also, surely rect is actually an inset, or have I just inverted my understanding of clip? I'd appreciate some advice. What I want to be able to do is (i) Define a rectangle using x, y, width and height (ii)Express the rectangle in TRBL form so that I can manipulate a divs clipping behaviour (iii)Change x, y, width or height and recalculate in terms of TRBL and goto (ii) I appreciate there are some other factors here, and some intermediary transforms to be done, but I've confused myself pretty badly- Can anyone give me some pointers?

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  • What is the proper way of hard-coding sections in a UITableView?

    - by Sheehan Alam
    I have a UITableView with 3 sections that are hard coded. Everything is working fine, but I am not sure if I am doing it correctly. Define number of rows in section: - (NSInteger)tableView:(UITableView *)tblView numberOfRowsInSection:(NSInteger)section { NSInteger rows; //Bio Section if(section == 0){ rows = 2; } //Profile section else if(section == 1){ rows = 5; } //Count section else if(section == 2){ rows = 3; } } return rows; } Here is where I build my cells: - (UITableViewCell *)tableView:(UITableView *)tblView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"Cell"; UITableViewCell *cell = [tblView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier] autorelease]; } cell.textLabel.numberOfLines = 5; cell.textLabel.font = [UIFont fontWithName:@"Helvetica" size:(10.0)]; cell.textLabel.lineBreakMode = UILineBreakModeWordWrap; if ([self.message_source isEqualToString:@"default"]) { if (indexPath.section == 0) { if (indexPath.row == 0) { cell.textLabel.text = [Utils formatMessage:[NSString stringWithFormat: @"%@", mySTUser.bio]]; cell.detailTextLabel.text = nil; } else if(indexPath.row == 1){ cell.textLabel.text = [NSString stringWithFormat: @"%@", mySTUser.website]; cell.detailTextLabel.text = nil; cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator; } } } //more code exists, but you get the point... Now I define my number of sections - (NSInteger)numberOfSectionsInTableView:(UITableView *)tblView { return 3; } Is this the proper way of hard-coding my UITableView? Will I run into any issues when cells are reused?

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  • Does anybody have any tips for managing polymorphic nested resources in Rails 3?

    - by Ryan
    in config/routes.rb: resources posts do resources comments end resources pictures do resources comments end I would like to allow for more things to be commented on as well. I'm currently using mongoid (mongomapper isn't as compatible with rails3 yet as I would like), and comments are an embedded resource (mongoid can't yet handle polymorphic relational resources), which means that I do need the parent resource in order to find the comment. Are there any elegant ways to handle some of the following problems: in my controller, I need to find the parent before finding the comment. if params[:post_id] parent = Post.find(params[:post_id] else if params[:picture_id] parent = Picture.find(params[:picture_id] end which is going to get messy if I start adding more things to be commentable also url_for([comment.parent,comment]) doesn't work, so I'm going to have to define something in my Comment model, but I think I'm also going to need to define an index route in the Comment model as well as potentially an edit and new route definition. There might be more issues that I have to deal with as I get further. I can't imagine I'm the first person to try and solve this problem, are there any solutions out there to make this more manageable?

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  • How can I modify the value of a string defined in a struct?

    - by Eric
    Hi, I have the following code in c++: #define TAM 4000 #define NUMPAGS 512 struct pagina { bitset<12> direccion; char operacion; char permiso; string *dato; int numero; }; void crearPagina(pagina* pag[], int pos, int dir) { pagina * paginas = (pagina*)malloc(sizeof(char) * TAM); paginas -> direccion = bitset<12> (dir); paginas -> operacion = 'n'; paginas -> permiso = 'n'; string **tempDato = &paginas -> dato; char *temp = " "; **tempDato = temp; paginas -> numero = 0; pag[pos] = paginas; } I want to modify the value of the variable called "string *dato" in the struct pagina but, everytime I want to assing a new value, the compiler throws a segmentation fault. In this case I'm using a pointer to string, but I have also tried with a string. In a few words I want to do the following: pagina - dato = "test"; Any idea? Thanks in advance!!!

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  • Why are argument substitutions not replaced during rescanning?

    - by James McNellis
    Consider the following macro definitions and invocation: #define x x[0] #define y(arg) arg y(x) This invocation expands to x[0] (tested on Visual C++ 2010, g++ 4.1, mcpp 2.7.2, and Wave). Why? Specifically, why does it not expand to x[0][0]? During macro replacement, A parameter in the replacement list...is replaced by the corresponding argument after all macros contained therein have been expanded. Before being substituted, each argument’s preprocessing tokens are completely macro replaced (C++03 §16.3.1/1). Evaluating the macro invocation, we take the following steps: The function-like macro y is invoked with x as the argument for its arg parameter The x in the argument is macro-replaced to become x[0] The arg in the replacement list is replaced by the macro-replaced value of the argument, x[0] The replacement list after substitution of all the parameters is x[0]. After all parameters in the replacement list have been substituted, the resulting preprocessing token sequence is rescanned...for more macro names to replace (C++03 §16.3.4/1). If the name of the macro being replaced is found during this scan of the replacement list...it is not replaced. Further, if any nested replacements encounter the name of the macro being replaced, it is not replaced (C++03 §16.3.4/2). The replacement list x[0] is rescanned (note that the name of the macro being replaced is y): x is identified as an object-like macro invocation x is replaced by x[0] Replacement stops at this point because of the rule in §16.3.4/2 preventing recursion. The replacement list after rescanning is x[0][0]. I have clearly misinterpreted something since all of the preprocessors I've tested say I am wrong. In addition, this example is a piece of a larger example in the C++0x FCD (at §16.3.5/5) and it too says that the expected replacement is x[0]. Why is x not replaced during rescanning? C99 and C++0x effectively have the same wording as C++03 in the quoted sections.

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  • Reading and writing in parallel

    - by Malfist
    I want to be able to read and write a large file in parallel, or if not in parallel, at least in blocks so that I don't use up so much memory. This is my current code: // Define memory stream which will be used to hold encrypted data. MemoryStream memoryStream = new MemoryStream(); // Define cryptographic stream (always use Write mode for encryption). CryptoStream cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write); //start encrypting using (BinaryReader reader = new BinaryReader(File.Open(fileIn, FileMode.Open))) { byte[] buffer = new byte[1024 * 1024]; int read = 0; do { read = reader.Read(buffer, 0, buffer.Length); cryptoStream.Write(buffer, 0, read); } while (read == buffer.Length); } // Finish encrypting. cryptoStream.FlushFinalBlock(); // Convert our encrypted data from a memory stream into a byte array. //byte[] cipherTextBytes = memoryStream.ToArray(); //write our memory stream to a file memoryStream.Position = 0; using (BinaryWriter writer = new BinaryWriter(File.Open(fileOut, FileMode.Create))) { byte[] buffer = new byte[1024 * 1024]; int read = 0; do { read = memoryStream.Read(buffer, 0, buffer.Length); writer.Write(buffer, 0, read); } while (read == buffer.Length); } // Close both streams. memoryStream.Close(); cryptoStream.Close(); As you can see, it reads the entire file into memory, encrypts it, then writes it out. If I happen to be encrypting files that are very large (2GB+) it tends not to work, or at the very least, consumes ~97% of my memory. How could I do it in a more effective manner?

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  • HIbernate 3.5.1 - can I just drop in EHCache 2.0.1?

    - by caerphilly
    I'm using Hibernate 3.5.1, which comes with EHCache 1.5 bundled. If I want to use the latest EHCache release (2.0.1), is it just a matter of removing the ehcache-1.5.jar from my project, and replacing with ehcache-core-2.0.1.jar? Any issues to be aware of? Also - is a cache "region" in the Hibernate mapping file that same as a cache "name" in the ehcache configuration xml? What I want to do is define 2 named cache regions - one for read-only reference entities that won't change (lookup lists etc), and one for all other entities. So in ehcache I want to define two elements; <cache name="readonly"> ... </cache> <cache name="mutable"> ... </cache> And then in my Hibernate mapping files, I will specify the cache to be used for each entity: <hibernate-mapping> <class name="lookuplist"> <cache region="readonly" usage="read-only"/> <property> ... </property> </class> </hibernate-mapping> Will that work? Some of the documentation seems to imply that a separate region/cache gets created for each mapped class... Thanks.

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  • How to Create the Upload File for Application Loader?

    - by Ohad Regev
    When I use Application Loader, I get to the point where it asks me to "Choose..." the file to be uploaded. If I understand correctly, it supposes to be the appName.app file I see under "Products" on my app bundle (I right click it and select "Show in Finder" to get to the specific file in library; then I'm supposed to ZIP it and the ZIP file is what I will choose in Application Loader). First, am I correct with this assumption? if yes... What should I define different in XCode than the way I used to build the application for testing (on simulator and on my personal iPhone)? Should I change the Info---Command-line build use from Debug to Release? How should I define the Build Settings---Code Signing section (in which field should I select the "iPhone Developer" option and in which should it be "iPhone Distribution")? Are there any other important Info/Build Settings/p.list/etc... fields I should relate to? any help will be appreciated...

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  • I can't compile this code

    - by heshim
    #include <stdio.h> #define IN 1 /* inside a word */ #define OUT 0 /* outside a word */ /* count lines, words, and characters in input */ main() { int c, nl, nw, nc, state; state = OUT; nl = nw = nc = 0; while ((c = getchar()) != EOF) { ++nc; if (c == '\n') ++nl; if (c == ' ' || c == '\n' || c = '\t') state = OUT; else if (state == OUT) { state = IN; ++nw; } } printf("%d %d %d\n", nl, nw, nc); } I got K&R book but there are some codes that don't compile ! it gives me - 19 C:\Users\Nom\Desktop\Untitled1.c invalid lvalue in assignment edit: now it works, thanks guys, but now it does nothing ! the printf statement doesn't work. It opens the dos console, I type anything and it just return a new line. I'm using Dev-C++ 4.9.9.2 I put the printf statement inside the while loop and it works now. thanks

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  • [MSBuild] Problem with setting properties 's values.

    - by Nam Gi VU
    Let's consider the below example. There, I have: target MAIN call target t then call target tt. target t call target ttt, target tt call target tttt. target t define property aa, target ttt modify aa. target tttt try to print property aa 's value. in short we have: MAIN - {t - {ttt-modify aa, define aa}, tt - tttt - print aa} But in target tttt, we can't "see" aa's updated value (by ttt)! Please help me to make that value visible to target tttt. Thank you! The whole script is as below: <Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003" DefaultTargets="MAIN" > <Target Name="MAIN" > <CallTarget Targets="t" /> <CallTarget Targets="tt" /> </Target> <Target Name="t"> <Message Text="t" /> <PropertyGroup> <aa>1</aa> </PropertyGroup> <CallTarget Targets="ttt" /> </Target> <Target Name="tt"> <Message Text="tt" /> <CallTarget Targets="tttt" /> </Target> <Target Name="ttt"> <PropertyGroup> <aa>122</aa> </PropertyGroup> <Message Text="ttt" /> </Target> <Target Name="tttt"> <Message Text="tttt" /> <Message Text="tttt:$(aa)" /> </Target> </Project>

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  • Setting initial state of a JSF component to invalid

    - by user359391
    Hi there I have a small JSF application where the user is required to enter some data about themselves. For each component on the page that has required="true" I want to show an icon depending if there is data in the field or not. My problem is that when the page is initially shown all fields are valid, even if they do not have any data in them. So my question is how I can set a component to be invalid based on if there is data in the field or not? After a submit of the page (or after the component loses focus) the icon is shown properly, it is only on the initial page load I have a problem. (i.e there is no post data) Here is my xhtml for a component that needs to be validated: <s:decorate id="employeeIdDecoration" template="/general/util/errorStyle.xhtml"> <ui:define name="label">#{messages['userdetails.employeeId']}</ui:define> <h:inputText value="#{authenticator.user.employeeId}" required="true"> <a4j:support event="onblur" reRender="employeeIdDecoration" bypassUpdates="true"/> </h:inputText> the template: <s:label styleClass="#{invalid?'error':''}"> <ui:insert name="label"/> <s:span styleClass="required" rendered="#{required}">*</s:span> </s:label> <span class="#{invalid?'error':''}"> <s:validateAll> <ui:insert/> </s:validateAll> <h:graphicImage value="/resources/redx.png" rendered="#{invalid}" height="16" width="16" style="vertical-align:middle;"/> <h:graphicImage value="/resources/Checkmark.png" rendered="#{!invalid}" height="16" width="16" style="vertical-align:middle;"/> </span> Any help will be appreciated.

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  • refactoring my code. My headers (Header Guard Issues)

    - by numerical25
    I had a post similar to this awhile ago based on a error I was getting. I was able to fix it but since then I been having trouble doing things because headers keep blocking other headers from using code. Honestly, these headers are confusing me and if anyone has any resources that will address these types of issues, that will be helpful. What I essentially want to do is be able to have rModel.h be included inside RenderEngine.h. every time I add rModel.h to RenderEngine.h, rModel.h is no longer able to use RenderEngine.h. (rModel.h has a #include of RenderEngine.h as well). So in a nutshell, RenderEngine and rModel need to use each others functionalities. On top of all this confusion, the Main.cpp needs to use RenderEngine. stdafx.h #include "targetver.h" #define WIN32_LEAN_AND_MEAN // Exclude rarely-used stuff from Windows headers // Windows Header Files: #include <windows.h> // C RunTime Header Files #include <stdlib.h> #include <malloc.h> #include <memory.h> #include <tchar.h> #include "resource.h" main.cpp #include "stdafx.h" #include "RenderEngine.h" #include "rModel.h" // Global Variables: RenderEngine go; rModel *g_pModel; ...code........... rModel.h #ifndef _MODEL_H #define _MODEL_H #include "stdafx.h" #include <vector> #include <string> #include "rTri.h" #include "RenderEngine.h" ........Code RenderEngine.h #pragma once #include "stdafx.h" #include "d3d10.h" #include "d3dx10.h" #include "dinput.h" #include "rModel.h" .......Code......

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  • casting char[][] to char** causes segfault?

    - by Earlz
    Ok my C is a bit rusty but I figured I'd make my next(small) project in C so I could polish back up on it and less than 20 lines in I already have a seg fault. This is my complete code: #define ROWS 4 #define COLS 4 char main_map[ROWS][COLS+1]={ "a.bb", "a.c.", "adc.", ".dc."}; void print_map(char** map){ int i; for(i=0;i<ROWS;i++){ puts(map[i]); //segfault here } } int main(){ print_map(main_map); //if I comment out this line it will work. puts(main_map[3]); return 0; } I am completely confused as to how this is causing a segfault. What is happening when casting from [][] to **!? That is the only warning I get. rushhour.c:23:3: warning: passing argument 1 of ‘print_map’ from incompatible pointer type rushhour.c:13:7: note: expected ‘char **’ but argument is of type ‘char (*)[5]’ Are [][] and ** really not compatible pointer types? They seem like they are just syntax to me.

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  • creating an object within a function of a program

    - by user1066524
    could someone please tell me what I need to do in order to create an object in a function. I will try to explain by making up some sort of example... Let's say I have a program named TimeScheduler.cpp that implements the class Schedule.h (and I have the implementation in a separate file Schedule.cpp where we define the methods). In the declaration file we have declared two constructors Schedule(); //the default and Schedule(int, int, int);//accepts three arguments to get to the point--let's say in the main program file TimeScheduler.cpp we created our own functions in this program apart from the functions inherited from the class Schedule. so we have our prototypes listed at the top. /*prototypes*/ void makeSomeTime(); etc..... we have main(){ //etc etc... } we then define these program functions void makeSomeTime(){ //process } let's say that inside the function makeSomeTime(), we would like to create an array of Schedule objects like this Schedule ob[]={ summer(5,14, 49), fall(9,25,50) }; what do I have to do to the function makeSomeTime() in order for it to allow me to create this array of objects. The reason I ask is currently i'm having difficulty with my own program in that it WILL allow me to create this array of objects in main()....but NOT in a function like I just gave an example of. The strange thing is it will allow me to create a dynamic array of objects in the function..... like Schedule *ob = new Schedule[n+1]; ob[2]= Schedule(x,y,z); Why would it let me assign to a non-dynamic array in main(), but not let me do that in the function?

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  • Postgresql Output column from another table

    - by muffin
    i'm using Postgresql, my question is specifically about querying from a table that's in another table and i'm really having trouble with this one. In fact, i'm absolutely mentally blocked. I'll try to define the relations of the tables as much as I can. I have a table entry which is like this: Each of the entries has a group_id; when they are 'advanced' to the next stage, the old entries are marked is_active = false, and a new assignment is done, so C & D are advanced stages of A & B. I have another table (which acts as a record keeper) , in which the storage_log_id refers to, this is the storage_log table : But then I have another table, to really find out where the entries are actually stored - storage table : To define my problem properly. Each entry has a storage_log_id (but some doesn't have yet), and a storage_log has a storage_id to refer to the actual table and find the storage label. The sql query i'm trying to do should output this one: Where The actual storage label is shown instead of the log id. This is so far what i've done: select e.id, e.group_id, e.name, e.stage, s.label from operational.entry e, operational.storage_log sl, operational.storage s where e.storage_log_id = sl.id and sl.storage_id = s.id But this just returns 3 rows, showing only the ones that have the seed_storage_log_id set; I should be able to see even those without logs, and especially the active ones. adding e.is_active = true to the condition makes the results empty. So, yeah i'm stuck. Need help, Thanks guys!

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  • Python: why can't descriptors be instance variables?

    - by Continuation
    Say I define this descriptor: class MyDescriptor(object): def __get__(self, instance, owner): return self._value def __set__(self, instance, value): self._value = value def __delete__(self, instance): del(self._value) And I use it in this: class MyClass1(object): value = MyDescriptor() >>> m1 = MyClass1() >>> m1.value = 1 >>> m2 = MyClass1() >>> m2.value = 2 >>> m1.value 2 So value is a class attribute and is shared by all instances. Now if I define this: class MyClass2(object) value = 1 >>> y1 = MyClass2() >>> y1.value=1 >>> y2 = MyClass2() >>> y2.value=2 >>> y1.value 1 In this case value is an instance attribute and is not shared by the instances. Why is it that when value is a descriptor it can only be a class attribute, but when value is a simple integer it becomes an instance attribute?

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  • guarantee child records either in one table or another, but not both?

    - by user151841
    I have a table with two child tables. For each record in the parent table, I want one and only one record in one of the child tables -- not one in each, not none. How to I define that? Here's the backstory. Feel free to criticize this implementation, but please answer the question above, because this isn't the only time I've encountered it: I have a database that holds data pertaining to user surveys. It was originally designed with one authentication method for starting a survey. Since then, requirements have changed, and now there are two different ways someone could sign on to start a survey. Originally I captured the authentication token in a column in the survey table. Since requirements changed, there are three other bits of data that I want to capture in authentication. So for each record in the survey table, I'm either going to have one token, or a set of three. All four of these are of different types, so my thought was, instead of having four columns where either one is going to be null, or three are going to be null ( or even worse, a bad mashup of either of those scenarios ), I would have two child tables, one for holding the single authentication token, the other for holding the three. Problem is, I don't know offhand how to define that in DDL. I'm using MySQL, so maybe there's a feature that MySQL doesn't implement that lets me do this.

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  • int array doesnt get char values

    - by user1780004
    I am absolutely brand new at programming and im not sure how to explain what im doing here. The whole purpose of this piece is to enter values and then print them out in the same order. Now I wanna quit from entering values when pressing 'q' and so I have to scanf for chars but when I assign them back to the int array the values are not the same. Hope that makes any sense to you but in any case heres my code: #include <stdio.h> #include <stdlib.h> #define SIZE 5000 define flush fflush(stdin) main() { int input[SIZE] = {0},i = 0; int counter = 0; char inputs, quit; do { system("cls"); printf("Input number ('q' to quit and display numbers entered): "); flush; scanf("%c",&inputs); flush; if (inputs == 'q') quit = 'q'; else { input[i] = inputs; counter++; i++; } } while (i < SIZE && quit != 'q'); for(i = 0; i < counter; i++){ printf("%i.%i\n", i + 1, input[i]); } system("pause"); } Ive been trying to do this on my own btw and also researched some information online regarding chars but couldnt find anything that would help me. Thanks a lot in advance.

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  • why doesnt this program print?

    - by Alex
    What I'm trying to do is to print my two-dimensional array but i'm lost. The first function is running perfect, the problem is the second or maybe the way I'm passing it to the "Print" function. #include <stdio.h> #include <stdlib.h> #define ROW 2 #define COL 2 //Memory allocation and values input void func(int **arr) { int i, j; arr = (int**)calloc(ROW,sizeof(int*)); for(i=0; i < ROW; i++) arr[i] = (int*)calloc(COL,sizeof(int)); printf("Input: \n"); for(i=0; i<ROW; i++) for(j=0; j<COL; j++) scanf_s("%d", &arr[i][j]); } //This is where the problem begins or maybe it's in the main void print(int **arr) { int i, j; for(i=0; i<ROW; i++) { for(j=0; j<COL; j++) printf("%5d", arr[i][j]); printf("\n"); } } void main() { int *arr; func(&arr); print(&arr); //maybe I'm not passing the arr right ? }

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  • Make All Types Constant by Default in C++

    - by Jon Purdy
    What is the simplest and least obtrusive way to indicate to the compiler, whether by means of compiler options, #defines, typedefs, or templates, that every time I say T, I really mean T const? I would prefer not to make use of an external preprocessor. Since I don't use the mutable keyword, that would be acceptable to repurpose to indicate mutable state. Potential (suboptimal) solutions so far: // I presume redefinition of keywords is implementation-defined or illegal. #define int int const #define ptr * const int i(0); int ptr j(&i); typedef int const Int; typedef int const* const Intp; Int i(0); Intp j(&i); template<class T> struct C { typedef T const type; typedef T const* const ptr; }; C<int>::type i(0); C<int>::ptr j(&i);

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