Visual C++ :: How To Get Pointer To CMyView Class From CMainFrame Class
Nov 29, 2013
My program is a basic MFC AppWizard (exe) created project in VC++ 6. In MainFrm.cpp, I am trying to access some user defined CMyView member functions. However when I try to do the standard procedure to get the CMyView pointer in MainFrm.cpp, I get the " ... 'CMyView' : undeclared identifier" error. To resolve this, I add " #include myView.h " at the top of MainFrm.h which then produces the following errors:
Code:
myview.h(21) : error C2143: syntax error : missing ';' before '*'
myview.h(21) : error C2501: 'CMyDoc' : missing storage-class or type specifiers
myview.h(21) : error C2501: 'GetDocument' : missing storage-class or type specifiers
What do these errors mean? Is there a simple way to access CMyView member functions from CMainFrame?
I have encountered a problem I can't see to solve. I want to access a function and can't seem to find the right combination to get me there. Here is what I am looking at:
CFoo1::CFoo2::GetStrDataC(int nRow) const
How do I call the GetStrDataC function from another class?
I create an instance of a base class (not derived class) and assign it to base class pointer. Then, I convert it to a pointer to a derived class and call methods on it.
why does it work, if there is a virtual table?
when will it fail?
// TestCastWin.cpp : Defines the entry point for the console application.//
In this book, item 3 is about never treat arrays polymorphically. In the latter part of this item, the author talks about the result of deleting an array of derived class objects through a base class pointer is undefined. What does it mean? I have an example here,
Code: class B { public: B():_y(1){} virtual ~B() { cout<<"~B()"<<endl;
[Code] ....
This sample code does exactly what I want. So does the author mean the way I did is undefined?
Is it possible to pass a class pointer as memory buffer across the socket? The above code is just an example. My question in general is, whether it's possible to pass any Classes pointer as a memory buffer across sockets.
My program (Test) is a basic MFC AppWizard (exe) created project. I have followed the steps in the link below to create a docked dialog box (myDialog) using VC++. [URL]...
The dialog box works, however, I have 2 issues that I am trying to resolve.
1) I have added a button to the Dialog box, however, when I run the application they start as disabled (note: the Disabled option on the Button Properties is unchecked). If I add function myDialog::OnButton to the myDialog class, the button remains disabled, however, if I add the function CTestView::OnButton to the View class, the button becomes active and works. How can I make the button work from the myDialog class?
2) I would like to be able to change an Edit box in the same dialog box when I click the button. How can I access the pointer to the myDialog from the View class?
I need understanding this block of code, particularly this line : *getLeftChild() { return this - _child; }
Code:
public class UpperNode { BOX _box; int _child; FORCEINLINE UpperNode *getLeftChild() { return this - _child; } ... };
Here I have this function:
Code: void UpperNode::visulization(int level) { if (isLeaf()) _box.visulization(); else if ((level > 0)) {
[Code] .....
It also makes calls for "getLeftChild()";
But I see that getLeftChild expects function pointer, and I absolutely have no clue where "this" comes from inside function body.
(return this - _child) - "this" has to be integer.
Or, if we gave pointer, and "this" is referring to some UpperNode, then I can't understand to which one, I have no UpperNode array defined or something. So if this functions is actually scaling pointer address, then scaling where to? I could comprehend it, if I had some array of UpperNodes, but not just class. I have UpperNodes array defined in other friendly class, but don't think they are related .....
I'm trying to implement a class hierarchy and a wrapper class with a pointer to the base class. The base class has operator< overloaded and the implementation makes use of virtual functions as some of the logic for sorting is in the derived classes. Unfortunately, when trying to use the base class operator< from the wrapper, I get a "pure virtual method called".
Below code is meant to illustrate my problem. Unfortunately it crashes on me (upon destruction of vec) and I cannot quite see, why. So two questions:
1. spot the error I made in the code below (having lived in Java-land for the last 5 years, I'm sure I just did some stupid error)?
2. How can I implement Wrapper::operator< to use Base::operator<? I know I could write a function and pass it to sort but I'm interessted if there is a way to actually use Base::operator<.
Code: Error1error LNK2019: unresolved external symbol "public: __thiscall ReachTop<class Character>::ReachTop<class Character>(class Character *)" (??0?$ReachTop@VCharacter@@@@QAE@PAVCharacter@@@Z) referenced in function "void __cdecl `dynamic initializer for 'gReachTop''(void)" (??__EgReachTop@@YAXXZ)Main.objDecisionTest
#include "IMyIntData.h" class MyIntData : public CPMUnknown<IMyIntData> {
I need to know what this syntax means (including MyIntData in angular brackets after parent class name) where IMyIntData is the Interface from where MyIntData is derived.
I want to ask about pointers to classes vs just classes. I have used classes such as QTimer with and without pointers, and I don't know when to use pointers. Sometimes you can't because a function returns a class, not a pointer to a class. But usually you can do either.
A pointer to base class, if assigned to a derived class, only points to the base part right? So you can only use the base part of the derived class with that pointer and no methods from the derived class?
If I need a static pointer to a class that is used globally(multiple files), and I only want to allocate memory once.
One way is to create a function that returns a static pointer of type class and call it where ever you need this pointer. My question is there another way to do this like with a header file and include the header file where you need to use the object of type class.
static class* function { static class c; if (c == NULL) { c = new class; } return c }
#include <iostream> #include <vector> #include <string> #include <map> using namespace std; struct bop { string realname; //real name
[Code] ....
Okay, so first thing's first. The program will not compile due to lines 39-45. If I were to change those pointers into regular objects, it will not change the values of my class object. So what is the right way to do this?
I want the user to be able to input the # of employers/programmers into the system. But I cannot do that with an array of classes because when declaring an array; the array size must be constant.
If i have a pointer array of classes, e.g. MyClass *foo; and if i try to delete this pointer delete [] foo; does it call a destructor of a class, or wahat happens? this is because i have another pointers in that class which are cleared in destructor.
Lets say we have a class that holds a pointer member to another object. If I delete that pointer in the destructor I get an error (and I understand why). My question is : is it possible to overcome that without memory leaks ?
1 #include<iostream> 2 using namespace std; 3 4 class A { 5 public: 6 ~A() { 7 cout<< "~A()" <<endl;
I am stucked in a problem of overloading arithmetic operators such as "+,*" for a class in the form
class Point { int N; // dimension of the point double *Pos; // length of N }
My assign operator is : Point& Point::operator= (const Point& pt) { N= pt.N; if(Pos == NULL) Pos = new double[N]; memcpy(Pos, pt.Pos, N*sizeof(double));
[Code] ....
The add operator "+" is: Point operator+( const Point& pt1, const Point& pt2 ) { Point ptr = Point(pt); // this is a constructor for (int i=0; i<pt1.N; i++) ptr.Pos[i] += pt2.Pos[i]; return ptr; }
Based on the above overloading, What I am going to do is :
P = alpha*P1 + beta*P2; // alpha and beta are double constants, P1 and P2 are Points objes
It is ok with Intel C++ 14.0 compiler, but does not work with the microsoft visual c++ 2012 compiler in debug mode in visual studio 2012.
I stepped in those operators and found that visual c++ compiler deconstructs the ptr in operators "*" and "+" before its return while intel c++ finished the operation P = alpha*P1 + beta*P2; and delete those ptrs at last.
Portability of my operator overloading is worse. How to get those arithmetic operators overloading for class with pointers in it.
