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  • rigidbody2d.Addforce( ) behaves wieirdly unity 4.3 [on hold]

    - by Lilz Votca Love
    So guys ive edited the question and here is what my problem is i have a player which has a rigidbody2d attached to it.my player is able to doublejump in the air nicely and stick to walls when colliding with them and slowly slides to the ground.All movement is handle through physics and no transform manipulations.here i did something similar to this in the FixedUpdate of my player. void FixedUpdate() { if(wall && Input.GetButtonDown("Jump")) { if(facingright)//player is facing the left side of the wall { rigidbody2D.Addforce(new vector2(-1f,2f)*jumpforce); /*Now the player should jump backwards following this directional vector and should follow a smooth curve which in this part works well*/ } else { rigidbody2D.Addforce(new vector2(1f,2f)*jumpforce); /*Now this is where everything gets complicated as you should have noticed this is the same directional vector only the opposite x axis value and the same amount of force is used but it behaves like the red curve in the picture below*/ } } } bad behaviour and vector in red .I tested the same thing(both addforce methods) for a simple jump and they exactly behave like mentionned above in the picture.so here is my problem.Jumping diagonally forward with rigidbody2d.addforce() do not have the same impact,do not follow the same curve as jumping the opposite direction with the same exact amount of force.if i could fix this or get past this i could implement a walljump system like a ninja jumping in zigzag between two opposite wall to climb them.Any ideas or alternatives?

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  • Extracting pair member in lambda expressions and template typedef idiom

    - by Nazgob
    Hi, I have some complex types here so I decided to use nifty trick to have typedef on templated types. Then I have a class some_container that has a container as a member. Container is a vector of pairs composed of element and vector. I want to write std::find_if algorithm with lambda expression to find element that have certain value. To get the value I have to call first on pair and then get value from element. Below my std::find_if there is normal loop that does the trick. My lambda fails to compile. How to access value inside element which is inside pair? I use g++ 4.4+ and VS 2010 and I want to stick to boost lambda for now. #include <vector> #include <algorithm> #include <boost\lambda\lambda.hpp> #include <boost\lambda\bind.hpp> template<typename T> class element { public: T value; }; template<typename T> class element_vector_pair // idiom to have templated typedef { public: typedef std::pair<element<T>, std::vector<T> > type; }; template<typename T> class vector_containter // idiom to have templated typedef { public: typedef std::vector<typename element_vector_pair<T>::type > type; }; template<typename T> bool operator==(const typename element_vector_pair<T>::type & lhs, const typename element_vector_pair<T>::type & rhs) { return lhs.first.value == rhs.first.value; } template<typename T> class some_container { public: element<T> get_element(const T& value) const { std::find_if(container.begin(), container.end(), bind(&typename vector_containter<T>::type::value_type::first::value, boost::lambda::_1) == value); /*for(size_t i = 0; i < container.size(); ++i) { if(container.at(i).first.value == value) { return container.at(i); } }*/ return element<T>(); //whatever } protected: typename vector_containter<T>::type container; }; int main() { some_container<int> s; s.get_element(5); return 0; }

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  • cannot evaluate expression because a native frame is on top of the call stack and system.accessviolationexception

    - by Joseph
    I have this code using c#. public partial class MainForm : Form { private CvCapture VideoCapture; private IplImage frame; private IplImage imgMain; public MainForm() { InitializeComponent(); } private void btnVideo_Click(object sender, EventArgs e) { double vidWidth, vidHeight; try { VideoCapture = highgui.CvCreateCameraCapture(0); } catch (Exception except) { MessageBox.Show(except.Message); } if (btnVideo.Text.CompareTo("Start Video") == 0) { if (VideoCapture.ptr == IntPtr.Zero) { MessageBox.Show("badtrip ah!!!"); return; } btnVideo.Text = "Stop Video"; highgui.CvSetCaptureProperty(ref VideoCapture, highgui.CV_CAP_PROP_FRAME_WIDTH, 640); highgui.CvSetCaptureProperty(ref VideoCapture, highgui.CV_CAP_PROP_FRAME_HEIGHT, 480); highgui.CvQueryFrame(ref VideoCapture); vidWidth = highgui.cvGetCaptureProperty(VideoCapture, highgui.CV_CAP_PROP_FRAME_WIDTH); vidHeight = highgui.cvGetCaptureProperty(VideoCapture, highgui.CV_CAP_PROP_FRAME_HEIGHT); picBoxMain.Width = (int)vidWidth; picBoxMain.Height = (int)vidHeight; timerGrab.Enabled = true; timerGrab.Interval = 42; timerGrab.Start(); } else { btnVideo.Text = "Start Video"; timerGrab.Enabled = false; if (VideoCapture.ptr == IntPtr.Zero) { highgui.CvReleaseCapture(ref VideoCapture); VideoCapture.ptr = IntPtr.Zero; } } } private void timerGrab_Tick(object sender, EventArgs e) { try { frame = highgui.CvQueryFrame(ref VideoCapture); if (frame.ptr == IntPtr.Zero) { timerGrab.Stop(); MessageBox.Show("??"); return; } imgMain = cxcore.CvCreateImage(cxcore.CvGetSize(ref frame), 8, 3); picBoxMain.Image = highgui.ToBitmap(imgMain, false); cxcore.CvReleaseImage(ref imgMain); //cxcore.CvReleaseImage(ref frame); } catch (Exception excpt) { MessageBox.Show(excpt.Message); } } } The problem is after i break all and step through the debugger the program stops at a certain code. the code where it stops is here: frame = highgui.CvQueryFrame(ref VideoCapture); the error is that it says that cannot evaluate expression because a native frame is on top of the call stack. and then when i try to shift+F11 it. there is another error saying that system.accessviolationexception. the stack trace says that: at System.Runtime.InteropServices.Marshal.CopyToManaged(IntPtr source, Object destination, Int32 startIndex, Int32 length) at CxCore.IplImage.get_ImageDataDb()

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  • 2D polygon triangulation

    - by logank9
    The code below is my attempt at triangulation. It outputs the wrong angles (it read a square's angles as 90, 90. 90, 176) and draws the wrong shapes. What am I doing wrong? //use earclipping to generate a list of triangles to draw std::vector<vec> calcTriDraw(std::vector<vec> poly) { std::vector<double> polyAngles; //get angles for(unsigned int i = 0;i < poly.size();i++) { int p1 = i - 1; int p2 = i; int p3 = i + 1; if(p3 > int(poly.size())) p3 -= poly.size(); if(p1 < 0) p1 += poly.size(); //get the angle from 3 points double dx, dy; dx = poly[p2].x - poly[p1].x; dy = poly[p2].y - poly[p1].y; double a = atan2(dy,dx); dx = poly[p3].x - poly[p2].x; dy = poly[p3].y - poly[p2].y; double b = atan2(dy,dx); polyAngles.push_back((a-b)*180/PI); } std::vector<vec> triList; for(unsigned int i = 0;i < poly.size() && poly.size() > 2;i++) { int p1 = i - 1; int p2 = i; int p3 = i + 1; if(p3 > int(poly.size())) p3 -= poly.size(); if(p1 < 0) p1 += poly.size(); if(polyAngles[p2] >= 180) { continue; } else { triList.push_back(poly[p1]); triList.push_back(poly[p2]); triList.push_back(poly[p3]); poly.erase(poly.begin()+p2); std::vector<vec> add = calcTriDraw(poly); triList.insert(triList.end(), add.begin(), add.end()); break; } } return triList; }

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  • How to use mmap to point to STL type?

    - by srikfreak
    I have a mmap typecast to a char pointer char *ptr; ptr = (char *)mmap(0, FILESIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); This was my earlier code. But now I want to use a map instead of char * as the requirements changed. Now, my map is declared as map i_s_map; How do I change my mmap call to point to the map?

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  • Variable sized packet structs with vectors

    - by Rev316
    Lately I've been diving into network programming, and I'm having some difficulty constructing a packet with a variable "data" property. Several prior questions have helped tremendously, but I'm still lacking some implementation details. I'm trying to avoid using variable sized arrays, and just use a vector. But I can't get it to be transmitted correctly, and I believe it's somewhere during serialization. Now for some code. Packet Header class Packet { public: void* Serialize(); bool Deserialize(void *message); unsigned int sender_id; unsigned int sequence_number; std::vector<char> data; }; Packet ImpL typedef struct { unsigned int sender_id; unsigned int sequence_number; std::vector<char> data; } Packet; void* Packet::Serialize(int size) { Packet* p = (Packet *) malloc(8 + 30); p->sender_id = htonl(this->sender_id); p->sequence_number = htonl(this->sequence_number); p->data.assign(size,'&'); //just for testing purposes } bool Packet::Deserialize(void *message) { Packet *s = (Packet*)message; this->sender_id = ntohl(s->sender_id); this->sequence_number = ntohl(s->sequence_number); this->data = s->data; } During execution, I simply create a packet, assign it's members, and send/receive accordingly. The above methods are only responsible for serialization. Unfortunately, the data never gets transferred. Couple of things to point out here. I'm guessing the malloc is wrong, but I'm not sure how else to compute it (i.e. what other value it would be). Other than that, I'm unsure of the proper way to use a vector in this fashion, and would love for someone to show me how (code examples please!) :) Edit: I've awarded the question to the most comprehensive answer regarding the implementation with a vector data property. Appreciate all the responses!

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  • Windows32 API: "mov edi,edi" on function entry?

    - by Ira Baxter
    I'm stepping through Structured Error Handling recovery code in Windows 7 (e.g, what happens after SEH handler is done and passes back "CONTINUE" code). Here's a function which is called: 7783BD9F mov edi,edi 7783BDA1 push ebp 7783BDA2 mov ebp,esp 7783BDA4 push 1 7783BDA6 push dword ptr [ebp+0Ch] 7783BDA9 push dword ptr [ebp+8] 7783BDAC call 778692DF 7783BDB1 pop ebp 7783BDB2 ret 8 I'm used to the function prolog of "push ebp/mov ebp,esp". What's the purpose of the "mov edi,edi"?

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  • retrieving information from web service calls

    - by Monte Chan
    Hi all, I am trying to retrieve information from a web service call. The following is what I have so far. In my text view, it is showing Map {item=anyType{key=TestKey; value=2;}; item=anyType{key=TestField; value=adsfasd; };} When I ran that in the debugger, I can see the information above in the variable, tempvar. But the question is, how do I retrieve the information (i.e. the actual values of "key" and "value" in each of the array positions)? Yes, I know there is a lot going on in onCreate and I will fix it later. Thanks in advance, Monte My codes are as follows, import java.util.Vector; import android.app.Activity; import android.os.Bundle; import android.widget.TextView; import org.ksoap2.SoapEnvelope; import org.ksoap2.serialization.SoapObject; import org.ksoap2.serialization.SoapSerializationEnvelope; import org.ksoap2.transport.AndroidHttpTransport; public class ViewHitUpActivity extends Activity { private static final String SOAP_ACTION = "test_function"; private static final String METHOD_NAME = "test_function"; private static final String NAMESPACE = "http://www.monteandjanicechan.com/"; private static final String URL = "http://www.monteandjanicechan.com/ws/test_ws.cfc?wsdl"; // private Object resultRequestSOAP = null; private TextView tv; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); SoapObject request = new SoapObject(NAMESPACE, METHOD_NAME); tv = (TextView)findViewById(R.id.people_view); //SoapObject request.addProperty("test_item", "1"); SoapSerializationEnvelope envelope = new SoapSerializationEnvelope(SoapEnvelope.VER11); envelope.setOutputSoapObject(request); AndroidHttpTransport androidHttpTransport = new AndroidHttpTransport(URL); try { androidHttpTransport.call(SOAP_ACTION, envelope); /* resultRequestSOAP = envelope.getResponse(); Vector tempResult = (Vector) resultRequestSOAP("test_functionReturn"); */ SoapObject resultsRequestSOAP = (SoapObject) envelope.bodyIn; Vector tempResult = (Vector) resultsRequestSOAP.getProperty("test_functionReturn"); int testsize = tempResult.size(); // SoapObject test = (SoapObject) tempResult.get(0); //String[] results = (String[]) resultRequestSOAP; Object tempvar = tempResult.elementAt(1); tv.setText(tempvar.toString()); } catch (Exception aE) { aE.printStackTrace (); tv.setText(aE.getClass().getName() + ": " + aE.getMessage()); } } }

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  • GAE Datastore: persisting referenced objects

    - by David
    Two "I'm sorries" to begin with: 1) I've looked for a solution (here, and elsewhere), and couldn't find the answer. 2) English is not my mother tongue, so I may have some typos and the sort - please ignore them. To the point: I am trying to persist Java objects to the GAE datastore. I am not sure as to how to persist object having ("non-trivial") referenced object. That is, assume I have the following. public class Father { String name; int age; Vector<Child> offsprings; //this is what I call "non-trivial" reference //ctor, getters, setters... } public class Child { String name; int age; Father father; //this is what I call "non-trivial" reference //ctor, getters, setters... } The name field is unique in each type domain, and is considered a Primary-Key. In order to persist the "trivial" (String, int) fields, all I need is to add the correct annotation. So far so good. However, I don't understand how should I persist the home-brewed (Child, Father) types referenced. Should I: Convert each such reference to hold the Primary-Key (a name String, in this example) instead of the "actual" object. So, Vector<Child> offsprings; becomes Vector<String> offspringsNames; ? If that is the case, how do I handle the object at run-time? Do I just query for the Primary-Key from Class.getName, to retrieve the refrenced objects? Convert each such reference to hold the actual Key provided to me by the Datastore upon the proper put() operation? So, Vector<Child> offsprings; becomes Vector<Key> offspringsHashKeys; ? I would very much appreciate all kinds of comments. I have read ALL the offical relevant GAE docs/example. Throughout, they always persist "trivial" references, natively supported by the Datastore (e.g. in the Guestbook example, only Strings, and Longs). Many thanks, David

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  • Does operator new allocate on THREAD heap?

    - by Jonas Byström
    My problem seems to be this: heap data allocated by one thread (that later dies) seems to die as well. As so: Thread X: starts Thread Y: starts Thread X: ptr = new some bytes Thread X: dies Thread Y: tries to use ptr - and crashes! So far, I've only seen this problem on Darwin (Mac OS 10.5 and 10.6), but haven't tried more other platforms than Windows and Linux (Ubuntu) where it works as expected. I've had this problem for some time, so any know-how or more information about this is highly appreciated!

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  • Should we denormalize database to improve performance?

    - by Groo
    We have a requirement to store 500 measurements per second, coming from several devices. Each measurement consists of a timestamp, a quantity type, and several vector values. Right now there is 8 vector values per measurement, and we may consider this number to be constant for needs of our prototype project. We are using HNibernate. Tests are done in SQLite (disk file db, not in-memory), but production will probably be MsSQL. Our Measurement entity class is the one that holds a single measurement, and looks like this: public class Measurement { public virtual Guid Id { get; private set; } public virtual Device Device { get; private set; } public virtual Timestamp Timestamp { get; private set; } public virtual IList<VectorValue> Vectors { get; private set; } } Vector values are stored in a separate table, so that each of them references its parent measurement through a foreign key. We have done a couple of things to ensure that generated SQL is (reasonably) efficient: we are using Guid.Comb for generating IDs, we are flushing around 500 items in a single transaction, ADO.Net batch size is set to 100 (I think SQLIte does not support batch updates? But it might be useful later). The problem Right now we can insert 150-200 measurements per second (which is not fast enough, although this is SQLite we are talking about). Looking at the generated SQL, we can see that in a single transaction we insert (as expected): 1 timestamp 1 measurement 8 vector values which means that we are actually doing 10x more single table inserts: 1500-2000 per second. If we placed everything (all 8 vector values and the timestamp) into the measurement table (adding 9 dedicated columns), it seems that we could increase our insert speed up to 10 times. Switching to SQL server will improve performance, but we would like to know if there might be a way to avoid unnecessary performance costs related to the way database is organized right now. [Edit] With in-memory SQLite I get around 350 items/sec (3500 single table inserts), which I believe is about as good as it gets with NHibernate (taking this post for reference: http://ayende.com/Blog/archive/2009/08/22/nhibernate-perf-tricks.aspx). But I might as well switch to SQL server and stop assuming things, right? I will update my post as soon as I test it.

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  • C++ Using a class template argument as a template argument for another type

    - by toefel
    Hey Everyone, I'm having this problem while writing my own HashTable. It all works, but when I try to templatize the thing, it gave me errors. I recreated the problem as follows: THIS CODE WORKS: typedef double Item; class A { public: A() { v.push_back(pair<string, Item>("hey", 5.0)); } void iterate() { for(Iterator iter = v.begin(); iter != v.end(); ++iter) cout << iter->first << ", " << iter->second << endl; } private: vector<pair<string, double> > v; typedef vector< pair<string, double> >::iterator Iterator; }; THIS CODE DOES NOT: template<typename ValueType> class B { public: B(){} void iterate() { for(Iterator iter = v.begin(); iter != v.end(); ++iter) cout << iter->first << ", " << iter->second << endl; } private: vector<pair<string, ValueType> > v; typedef vector< pair<string, ValueType> >::iterator Iterator; }; the error messages: g++ -O0 -g3 -Wall -c -fmessage-length=0 -omain.o ..\main.cpp ..\main.cpp:50: error: type std::vector<std::pair<std::string, ValueType>, std::allocator<std::pair<std::string, ValueType> > >' is not derived from typeB' ..\main.cpp:50: error: ISO C++ forbids declaration of `iterator' with no type ..\main.cpp:50: error: expected `;' before "Iterator" ..\main.cpp: In member function `void B::iterate()': ..\main.cpp:44: error: `Iterator' was not declared in this scope ..\main.cpp:44: error: expected `;' before "iter" ..\main.cpp:44: error: `iter' was not declared in this scope Does anybody know why this is happening? Thanks!

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  • How can I get valgrind to tell me the address of each non-freed block of memory?

    - by James
    Valgrind tells me function xxx allocated memory which was not freed. Fine. It's proving more difficult than usual to trace however. To this end I have created numerous: #ifdef DEBUG fprintf(stderr, "something happening:%lx\n", (unsigned long)ptr); #endif So I just need to match these ptr addresses that are displayed with the addresses of non-freed memory. How can I get valgrind to tell me the address of each non-freed block of memory?

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  • How can I prevent segmentation faults in my program?

    - by worlds-apart89
    I have a C assignment. It is a lot longer than the code shown below, and we are given the function prototypes and instructions only. I have done my best at writing code, but I am stuck with segmentation faults. When I compile and run the program below on Linux, at "735 NaN" it will terminate, indicating a segfault occurred. Why? What am I doing wrong? Basically, the program does not let me access table-list_array[735]-value and table-list_array[735]-key. This is of course the first segfault. There might be more following index 735. #include <stdio.h> #include <stdlib.h> typedef struct list_node list_node_t; struct list_node { char *key; int value; list_node_t *next; }; typedef struct count_table count_table_t; struct count_table { int size; list_node_t **list_array; }; count_table_t* table_allocate(int size) { count_table_t *ptr = malloc(sizeof(count_table_t)); ptr->size = size; list_node_t *nodes[size]; int k; for(k=0; k<size; k++){ nodes[k] = NULL; } ptr->list_array = nodes; return ptr; } void table_addvalue(count_table_t *table) { int i; for(i=0; i<table->size; i++) { table->list_array[i] = malloc(sizeof(list_node_t)); table->list_array[i]->value = i; table->list_array[i]->key = "NaN"; table->list_array[i]->next = NULL; } } int main() { count_table_t *table = table_allocate(1000); table_addvalue(table); int i; for(i=0; i<table->size; i++) printf("%d %s\n", table->list_array[i]->value, table->list_array[i]->key); return 0; }

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  • Emacs, C++ code completion for vectors

    - by Caglar Toklu
    Hi, I am new to Emacs, and I have the following code as a sample. I have installed GNU Emacs 23.1.1 (i386-mingw-nt6.1.7600), installed cedet-1.0pre7.tar.gz. , installed ELPA, and company. You can find my simple Emacs configuration at the bottom. The problem is, when I type q[0] in main() and press . (dot), I see the 37 members of the vector, not Person although first_name and last_name are expected. The completion works as expected in the function greet() but it has nothing to do with vector. My question is, how can I accomplish code completion for vector elements too? #include <iostream> #include <vector> using namespace std; class Person { public: string first_name; string last_name; }; void greet(Person a_person) { // a_person.first_name is completed as expected! cout << a_person.first_name << "|"; cout << a_person.last_name << endl; }; int main() { vector<Person> q(2); Person guy1; guy1.first_name = "foo"; guy1.last_name = "bar"; Person guy2; guy2.first_name = "stack"; guy2.last_name = "overflow"; q[0] = guy1; q[1] = guy2; greet(guy1); greet(guy2); // cout q[0]. I want to see first_name or last_name here! } My Emacs configuration: ;;; This was installed by package-install.el. ;;; This provides support for the package system and ;;; interfacing with ELPA, the package archive. ;;; Move this code earlier if you want to reference ;;; packages in your .emacs. (when (load (expand-file-name "~/.emacs.d/elpa/package.el")) (package-initialize)) (load-file "~/.emacs.d/cedet/common/cedet.el") (semantic-load-enable-excessive-code-helpers) (require 'semantic-ia) (global-srecode-minor-mode 1) (semantic-add-system-include "/gcc/include/c++/4.4.2" 'c++-mode) (semantic-add-system-include "/gcc/i386-pc-mingw32/include" 'c++-mode) (semantic-add-system-include "/gcc/include" 'c++-mode) (defun my-semantic-hook () (imenu-add-to-menubar "TAGS")) (add-hook 'semantic-init-hooks 'my-semantic-hook)

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  • Remove never-run call to templated function, get allocation error on run-time

    - by Narfanator
    First off, I'm a bit at a loss as to how to ask this question. So I'm going to try throwing lots of information at the problem. Ok, so, I went to completely redesign my test project for my experimental core library thingy. I use a lot of template shenanigans in the library. When I removed the "user" code, the tests gave me a memory allocation error. After quite a bit of experimenting, I narrowed it down to this bit of code (out of a couple hundred lines): void VOODOO(components::switchBoard &board){ board.addComponent<using_allegro::keyInputs<'w'> >(); } Fundementally, what's weirding me out is that it appears that the act of compiling this function (and the template function it then uses, and the template functions those then use...), makes this bug not appear. This code is not being run. Similar code (the same, but for different key vals) occurs elsewhere, but is within Boost TDD code. I realize I certainly haven't given enough information for you to solve it for me; I tried, but it more-or-less spirals into most of the code base. I think I'm most looking for "here's what the problem could be", "here's where to look", etc. There's something that's happening during compile because of this line, but I don't know enough about that step to begin looking. Sooo, how can a (presumably) compilied, but never actually run, bit of templated code, when removed, cause another part of code to fail? Error: Unhandled exceptionat 0x6fe731ea (msvcr90d.dll) in Switchboard.exe: 0xC0000005: Access violation reading location 0xcdcdcdc1. Callstack: operator delete(void * pUser Data) allocator< class name related to key inputs callbacks ::deallocate vector< same class ::_Insert_n(...) vector< " " ::insert(...) vector<" "::push_back(...) It looks like maybe the vector isn't valid, because _MyFirst and similar data members are showing values of 0xcdcdcdcd in the debugger. But the vector is a member variable...

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  • Simplifying const Overloading?

    - by templatetypedef
    Hello all- I've been teaching a C++ programming class for many years now and one of the trickiest things to explain to students is const overloading. I commonly use the example of a vector-like class and its operator[] function: template <typename T> class Vector { public: T& operator[] (size_t index); const T& operator[] (size_t index) const; }; I have little to no trouble explaining why it is that two versions of the operator[] function are needed, but in trying to explain how to unify the two implementations together I often find myself wasting a lot of time with language arcana. The problem is that the only good, reliable way that I know how to implement one of these functions in terms of the other is with the const_cast/static_cast trick: template <typename T> const T& Vector<T>::operator[] (size_t index) const { /* ... your implementation here ... */ } template <typename T> T& Vector<T>::operator[] (size_t index) { return const_cast<T&>(static_cast<const Vector&>(*this)[index]); } The problem with this setup is that it's extremely tricky to explain and not at all intuitively obvious. When you explain it as "cast to const, then call the const version, then strip off constness" it's a little easier to understand, but the actual syntax is frightening,. Explaining what const_cast is, why it's appropriate here, and why it's almost universally inappropriate elsewhere usually takes me five to ten minutes of lecture time, and making sense of this whole expression often requires more effort than the difference between const T* and T* const. I feel that students need to know about const-overloading and how to do it without needlessly duplicating the code in the two functions, but this trick seems a bit excessive in an introductory C++ programming course. My question is this - is there a simpler way to implement const-overloaded functions in terms of one another? Or is there a simpler way of explaining this existing trick to students? Thanks so much!

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  • Split string in C every white space

    - by redsolja
    I want to write a program in C that displays each word of a whole sentence (taken as input) at a seperate line. This is what i have done so far: void manipulate(char *buffer); int get_words(char *buffer); int main(){ char buff[100]; printf("sizeof %d\nstrlen %d\n", sizeof(buff), strlen(buff)); // Debugging reasons bzero(buff, sizeof(buff)); printf("Give me the text:\n"); fgets(buff, sizeof(buff), stdin); manipulate(buff); return 0; } int get_words(char *buffer){ // Function that gets the word count, by counting the spaces. int count; int wordcount = 0; char ch; for (count = 0; count < strlen(buffer); count ++){ ch = buffer[count]; if((isblank(ch)) || (buffer[count] == '\0')){ // if the character is blank, or null byte add 1 to the wordcounter wordcount += 1; } } printf("%d\n\n", wordcount); return wordcount; } void manipulate(char *buffer){ int words = get_words(buffer); char *newbuff[words]; char *ptr; int count = 0; int count2 = 0; char ch = '\n'; ptr = buffer; bzero(newbuff, sizeof(newbuff)); for (count = 0; count < 100; count ++){ ch = buffer[count]; if (isblank(ch) || buffer[count] == '\0'){ buffer[count] = '\0'; if((newbuff[count2] = (char *)malloc(strlen(buffer))) == NULL) { printf("MALLOC ERROR!\n"); exit(-1); } strcpy(newbuff[count2], ptr); printf("\n%s\n",newbuff[count2]); ptr = &buffer[count + 1]; count2 ++; } } } Although the output is what i want, i have really many black spaces after the final word displayed, and the malloc() returns NULL so the MALLOC ERROR! is displayed in the end. I can understand that there is a mistake at my malloc() implementation but i do not know what it is. Is there another more elegant - generally better way to do it? Thanks in advance.

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  • A few questions about char pointers.

    - by m4design
    1- How does this work: char *ptr = "hi"; Now the compiler will put this string in the memory (I'm guessing the stack), and create a pointer to it? Is this is how it works? 2- Also if it is created locally in a function, when the function returns will the memory occupied by the string be freed? 3- Last but not least, why is this not allowed: ptr[0] = 'H'; ?

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  • I am getting the below mentioned error in my program. what will be the solution?

    - by suvirai
    // Finaldesktop.cpp : Defines the entry point for the console application. // include include include include include using namespace std; int SearchDirectory(vector &refvecFiles, const string &refcstrRootDirectory, const string &refcstrExtension, bool bSearchSubdirectories = true) { string strFilePath; // Filepath string strPattern; // Pattern string strExtension; // Extension HANDLE hFile; // Handle to file WIN32_FIND_DATA FileInformation; // File information strPattern = refcstrRootDirectory + "\."; hFile = FindFirstFile(strPattern.c_str(), &FileInformation); if(hFile != INVALID_HANDLE_VALUE) { do { if(FileInformation.cFileName[0] != '.') { strFilePath.erase(); strFilePath = refcstrRootDirectory + "\" + FileInformation.cFileName; if(FileInformation.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) { if(bSearchSubdirectories) { // Search subdirectory int iRC = SearchDirectory(refvecFiles, strFilePath, refcstrExtension, bSearchSubdirectories); if(iRC) return iRC; } } else { // Check extension strExtension = FileInformation.cFileName; strExtension = strExtension.substr(strExtension.rfind(".") + 1); if(strExtension == refcstrExtension) { // Save filename refvecFiles.push_back(strFilePath); } } } } while(FindNextFile(hFile, &FileInformation) == TRUE); // Close handle FindClose(hFile); DWORD dwError = GetLastError(); if(dwError != ERROR_NO_MORE_FILES) return dwError; } return 0; } int main() { int iRC = 0; vector vecAviFiles; vector vecTxtFiles; // Search 'c:' for '.avi' files including subdirectories iRC = SearchDirectory(vecAviFiles, "c:", "avi"); if(iRC) { cout << "Error " << iRC << endl; return -1; } // Print results for(vector::iterator iterAvi = vecAviFiles.begin(); iterAvi != vecAviFiles.end(); ++iterAvi) cout << *iterAvi << endl; // Search 'c:\textfiles' for '.txt' files excluding subdirectories iRC = SearchDirectory(vecTxtFiles, "c:\textfiles", "txt", false); if(iRC) { cout << "Error " << iRC << endl; return -1; } // Print results for(vector::iterator iterTxt = vecTxtFiles.begin(); iterTxt != vecTxtFiles.end(); ++iterTxt) cout << *iterTxt << endl; // Wait for keystroke _getch(); return 0; }

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  • Collision Detection probelm (intersection with plane)

    - by Demi
    I'm doing a scene using openGL (a house). I want to do some collision detection, mainly with the walls in the house. I have tried the following code: // a plane is represented with a normal and a position in space Vector planeNor(0,0,1); Vector position(0,0,-10); Plane p(planeNor,position); Vector vel(0,0,-1); double lamda; // this is the intersection point Vector pNormal; // the normal of the intersection // this method is from Nehe's Lesson 30 coll= p.TestIntersionPlane(vel,Z,lamda,pNormal); glPushMatrix(); glBegin(GL_QUADS); if(coll) glColor3f(1,0,0); else glColor3f(1,1,1); glVertex3d(0,0,-10); glVertex3d(3,0,-10); glVertex3d(3,3,-10); glVertex3d(0,3,-10); glEnd(); glPopMatrix(); Nehe's method: #define EPSILON 1.0e-8 #define ZERO EPSILON bool Plane::TestIntersionPlane(const Vector3 & position,const Vector3 & direction, double& lamda, Vector3 & pNormal) { double DotProduct=direction.scalarProduct(normal); // Dot Product Between Plane Normal And Ray Direction double l2; // Determine If Ray Parallel To Plane if ((DotProduct<ZERO)&&(DotProduct>-ZERO)) return false; l2=(normal.scalarProduct(position))/DotProduct; // Find Distance To Collision Point if (l2<-ZERO) // Test If Collision Behind Start return false; pNormal= normal; lamda=l2; return true; } Z is initially (0,0,0) and every time I move the camera towards the plane, I reduce its z component by 0.1 (i.e. Z.z-=0.1 ). I know that the problem is with the vel vector, but I can't figure out what the right value should be. Can anyone please help me?

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  • How can I represent a line of music notes in a way that allows fast insertion at any index?

    - by chairbender
    For "fun", and to learn functional programming, I'm developing a program in Clojure that does algorithmic composition using ideas from this theory of music called "Westergaardian Theory". It generates lines of music (where a line is just a single staff consisting of a sequence of notes, each with pitches and durations). It basically works like this: Start with a line consisting of three notes (the specifics of how these are chosen are not important). Randomly perform one of several "operations" on this line. The operation picks randomly from all pairs of adjacent notes that meet a certain criteria (for each pair, the criteria only depends on the pair and is independent of the other notes in the line). It inserts 1 or several notes (depending on the operation) between the chosen pair. Each operation has its own unique criteria. Continue randomly performing these operations on the line until the line is the desired length. The issue I've run into is that my implementation of this is quite slow, and I suspect it could be made faster. I'm new to Clojure and functional programming in general (though I'm experienced with OO), so I'm hoping someone with more experience can point out if I'm not thinking in a functional paradigm or missing out on some FP technique. My current implementation is that each line is a vector containing maps. Each map has a :note and a :dur. :note's value is a keyword representing a musical note like :A4 or :C#3. :dur's value is a fraction, representing the duration of the note (1 is a whole note, 1/4 is a quarter note, etc...). So, for example, a line representing the C major scale starting on C3 would look like this: [ {:note :C3 :dur 1} {:note :D3 :dur 1} {:note :E3 :dur 1} {:note :F3 :dur 1} {:note :G3 :dur 1} {:note :A4 :dur 1} {:note :B4 :dur 1} ] This is a problematic representation because there's not really a quick way to insert into an arbitrary index of a vector. But insertion is the most frequently performed operation on these lines. My current terrible function for inserting notes into a line basically splits the vector using subvec at the point of insertion, uses conj to join the first part + notes + last part, then uses flatten and vec to make them all be in a one-dimensional vector. For example if I want to insert C3 and D3 into the the C major scale at index 3 (where the F3 is), it would do this (I'll use the note name in place of the :note and :dur maps): (conj [C3 D3 E3] [C3 D3] [F3 G3 A4 B4]), which creates [C3 D3 E3 [C3 D3] [F3 G3 A4 B4]] (vec (flatten previous-vector)) which gives [C3 D3 E3 C3 D3 F3 G3 A4 B4] The run time of that is O(n), AFAIK. I'm looking for a way to make this insertion faster. I've searched for information on Clojure data structures that have fast insertion but haven't found anything that would work. I found "finger trees" but they only allow fast insertion at the start or end of the list. Edit: I split this into two questions. The other part is here.

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