I need a static hash table to keep track of all objects of a particular type that are instantiated in a Qt application but I have never used a template class as a static member object before and I can't seem to figure out how to initialize it. QHash is the hash table class that follows the template convetion:
template<class key, class data>
QString is probably self explanatory.
Example Header:
class MyClass { ... private: static QHash<QString, MyClass*> instanceTable; }
Here is my source that doesn't compile.
Example Source
#include header.h // using default constructor for table... QHash<QString key, MyClass* instance> MyClass::instanceTable(); // gives Error below. // Error in above line is "Declaration is incompatible with QHash<QString, Myclass*>"
I have tried doing it a number of different ways and none of them work. How do you initialize a static template object?
This problem just seems really strange to me because it is simple yet for some reason my class cannot pass into another class. The class PASS_OBJECT has a static array (even with 1 element this doesn't work) and when I try to pass this class (after it is initialized) I seem to lose the data inside the PASS_OBJECT. Not only that but even when I declared the class OBJECT with the type of PASS_OBJECT<int> I seem to lose the integer 99. Here's the code, note that if you comment out line 89, 92 and 93 you will notice that line 90 outputs In main 2: 99 just fine but it doesn't otherwise???
#include <iostream> const int size = 1; template <class T> class PASS_OBJECT; template <class S> class OBJECT {
I see many time where static data member is used to count creations of objects -
i.e.
1. the static data member is init to 0
2. the static data member is incremented by 1, in the Class' constructor, every time an object is created
However, if you define a global object of a class,
How can you tell that the static data member is initialized BEFORE the constructor of the global object is called? (i.e. before the global object is created).
Because to my understanding, you do not know in advance the order of global objects' creation -
so the Global Object could be created BEFORE the static data member was created and initialized.
Code: class A { std::map<std::string, Unit*> aMap; class B
[Code] .....
This code snippet results in "A non-static member reference must be made relative to a specific object". When I make callA() static, this error goes away, but there is problem with aMap.
will copy constructor does object initialization using another already created object? I understand that it can be applied for object initialization and not for assignment.Is it correct?
I have a method to take a Tile object and make an instances of it based on some data from the original object. Than it is suppose to manipulate the a specific instance and save the results. The first loop through it works but it changes all instance as well as the base.
public static int recurse(int count, Tile[,] b,Huristic h,int check) { if (check==1) { boardState.Add(B)/>; return check; } if (check == 0)
this function will return a temporary integer now void fun1(const int & num); this function can receive from myfun().BUT void fun2(int & num); this function cannot receive from myfun() Why is that, Moreover what is lifetime of a temporary object like one returned in myfun() ???
I am using the above code to retrive an item selected by user,But this line is giving an exception "Null Reference Exception, Object reference not set to an instance of an object"
#include <iostream> #include "curve1.h" #include "curve2.h" using namespace std; int main() { Curve1 curve1Obj; Curve2 curve2Obj;
[Code]...
Base class Score has two derived classes Curve1 and Curve2. There are two curve() functions, one is in Curve1 and other in Curve2 classes. getSize() returns the value of iSize.
My base class header score.h looks like this:
#ifndef SCORE_H #define SCORE_H class Score { private: int *ipScore; float fAverage; int iSize;
[Code]...
You can see that I have used curve1Obj to enter scores, calculate average and output. So if I call getSize() function with cuve1Obj, it gives the right size that I took from user in enterScores() function. Also the result is same if I call getSize() in score.cpp definition file in any of the functions (obviously). .....
The problem is when I call curve() function of Curve2 class in main (line 23) with the object curve2Obj, it creates a new set of ipScore, fAverage and iSize (i think?) with garbage values. So when I call getSize() in curve() definition in curve2.cpp, it outputs the garbage. .....
How can I cause it to return the old values that are set in curve1.cpp?
Here is my curve2.cpp
#include <iostream> #include "curve2.h" using namespace std; void Curve2::curve() { cout << "getSize() returns: " << getSize() << endl; // out comes the garbage }
Can I use a function to simply put values from old to new variables? If yes then how?
I am writing a program which is using SDL library. I have two different classes which one of them is Timer Class and the other is EventHandling Class.
I need to use some member functions and variables of Timer in some Eventhandling Class member functions, Although I want to define an object of Timer in int main {} and relate it to its member function that has been used in Eventhandling member function in order that it becomes easier to handle it, I mean that I want to have for example two objects of timer and two objects of Eventhandling class for two different users.
I do not know how to relate an object of a class from int main{} to its member function which is being used in another class member function.
I have two classes one called Date and the other is University , Date class has two overloaded operators , ostream and istream to take in the data and print them out :
The University class has an object of type Date called establishDate and I must use this to print out the date along with the University name and location, here's University class :
University.h
class University { public: University (); // constructor friend ostream & operator<<(ostream & out, University & x); // print the university data friend istream & operator>>(istream & in, University & x); // to read university data
In Visual Studio 2010 C++ I have a series of existing text objects The text properties names are item1_lbl, item2_lbl, item3_lbl, ….
Based on a selection I want to change an object. I generate the name of the object I want to change in a string so from this string is there a way to get a pointer to the correct text object that is same name?
Sandy is of class Person, who converts to Muslim and takes on a new name Fatima, and has all the attributes of Sandy, with new Muslim attributes (e.g. religion == Islam, etc..). At this point, Sandy can be deleted, and Fatima, now of class Muslim will play Sandy's role henceforth. The problem is that due to her new address, all the people who knew Sandy does not know Fatima. Manually changing Sandy's address to Fatima's address for all those people who knew Sandy is clearly not an acceptable method. I looked through all the design patterns and cannot find one to solve this problem. how to improve the design? Here's my simplified code showing the problem:
#include <iostream> #include <string> #include <typeinfo> class Person { std::string name; Person* bestFriend;
[Code]...
Output:
sandy = 0x32658, 6Person Mary's best friend is Sandy. fatima = 0x23fec0, 6Muslim Mary's best friend is Sandy.
Of course, we want to have: Mary's best friend is Fatima,. with mary->getBestFriend()->getReligion() == Islam, etc... How to redesign the whole thing so that this is automated (assume there are thousands of people who know her)?
I have a class MySeqBuildBlockModule that I am inheriting from: public SeqBuildBlock. Other than constructor and destructor, this class MySeqBuildBlockModule has a method: prep.
class MySeqBuildBlockModule: public SeqBuildBlock { friend class SeqBuildBlockIRns; public: MySeqBuildBlockModule (SBBList* pSBBList0, long TI1_In, long TI2_In)// more arguements in this constructor of derived class : SeqBuildBlock (pSBBList0)
[code]....
I would have like to intiantiate an object "myIRns_3" of a class defined in third party library
SeqBuildBlockIRns myIRns_3(pSBBList2);
and would like to access it from the prep function as:
I tried to instantiate following in either private section or in constructor; but w/o any success:
SeqBuildBlockIRns myIRns_3(pSBBList2);
ERRORS encountered:
When I tried to do it inside the constructor, I get the following errors:
MySBBModule.h(113) : error C2065: 'myIRns_3' : undeclared identifier MySBBModule.h(113) : error C2228: left of '.getEnergyPerRequest' must have class/struct/union type MySBBModule.h(116) : error C2065: 'pSBBList' : undeclared identifier MySBBModule.h(116) : error C2227: left of '->prepSBBAll' must point to class/struct/union
When I tried to do it in private section, I get the following errors:
MySBBModule.h(106) : error C2061: syntax error : identifier 'pSBBList2' MySBBModule.h(113) : error C2228: left of '.getEnergyPerRequest' must have class/struct/union type MySBBModule.h(116) : error C2065: 'pSBBList' : undeclared identifier MySBBModule.h(116) : error C2227: left of '->prepSBBAll' must point to class/struct/union
I am having trouble working with third party dll's, libs and header files. I am trying to call a function.here is the function that is suppose to be called.
Name IN/OUT Description m_environment IN Optional. Possible values are SANDBOX (default) and LIVE. m_strConsumerKey IN OAuth consumer key provided by E*TRADE m_strConsumerSecret IN OAuth consumer secret provided by E*TRADE m_strToken OUT Returned by the function if successful m_strTokenSecret OUT Returned by the function if successful m_strCallback IN Optional; default value is "oob"