I am essentially trying to get a value from a 'Matrix' that is created. Using a function in the class where the matrix is created. But when trying to do this I get the error: Call to non-static member function without an object argument in this line when trying to call the function:
Matrix::get(sizeR, sizeC);
if we don't provide the acces modifiers for base class and we need to manipulate the private data of base class in derived class. Is there anyway to acces the private data members? Here's a coding example
class A {
private :
int a;
};
class B : public class A {
public :
void displayA() { cout<<a<<endl; }
};
how i can acces the a of base class A in derived class B without acces modifiers.
So I have an ImageManager class, Board class, and Box class. In Board.h I can declare ImageManager imgr; and in Board's constructor I can use imgr and its functions and such. However, in Box.h when I try and declare ImageManager imgr; I get the error "cannot access member declared in class ImageManager". Both declarations are under private, and exactly the same, but one doesn't work. Also, is there a way to only have one instance of ImageManager?
View 19 Replies View RelatedI am trying to access a variable from another class through another class but it is not returning its "instance"?
Example:
Class View
Code:
...
V3D_Viewer viewer;
...
Class MainWindow
Code:
...
viewer* myView;
myView = new viewer();
...
Class Test
Code:
...
MainWindow window;
window.myView->setBackgroundColor(WHITE);
...
I am new to c++ references and pointers,
I cannot wrap my head as to how to access my enum class Azimuth.
Code: #ifndef BOUSOLE_H
#define BOUSOLE_H
#include <iostream>
#include <string>
#include "StringHandler.h"
class Bousole{
[code]...
And here is where I am trying to access my enum for testing/understanding purposes
Code: #include "Bousole.h"
using namespace std;
int main (int argc, char *argv[]){
cout <<"Start bousole" << endl;
Bousole b;
[Code] ....
how can I make the queue of type pcb
and how to access pid in other clases?
class myCls{
int x;
};
and then I create:
myCls c1;
and now:
is there way that I go like: cout << c1;
not overloading << operator;
and it shows me a value of c1.x?
just wanna replace c1 with that value;
I need sth similar to indexer from c#.
I have the following scenario :
Code:
class test {
public :
int num;
};
int main() {
test t1;
test *ptr = &t1;
int test :: *mem_ptr = &test::num;
}
I need to access mem_ptr (pointer to a class member) through :
a. object (t1)
b. pointer to the object (ptr).
How can i do that ?
I have 2 c++ libraries called "Lib1" and "Lib2". Both libraries have same class called "Total.h and Total.cpp"
I want to access lib1 class in lib2. since it has same class (i.e same header file), i couldn't refer lib1's members in lib2.
Lib 1 :
Total.h :
class Total {
public:
static void Test(double);
[Code] .....
How to access another library which has same name and how to add header file ?
This question is more from a design point-of-view rather than coding it to be a fully functional.
So here it goes:
I have multiple files which each require their own object of same class type (ref. First Class). File contents are read from a file to a unordered_map<std::string, std::vector<std::string>> which is either private or protected member inside First Class. First Class does not need any public functions to add, remove or change the data during runtime, but changes are only being made by checking if the file size has changed during the day, if the size is not equal to the last check, map gets updated.
Now, I have a Second Class which is a data handler class. It has public member functions with arguments that needs to be get from First Class's unordered_map using const_iterator. Which way to go with design and implementation.
I know there's two methods to do this. Re-doing handler class is also not out of the question. These two methods I'm aware of are:
1. Declare these maps to local scope, build few global functions and here we go. (Probably the easiest way.)
2. Create public member functions to a First Class which either return a pointer or a reference to a protected/private member. (I'm under the impression that I really shouldn't be doing this because of a bad coding practice.)
Note that I don't need any code here, just some other point-of-views regarding the subject itself for learning better coding practices.
I have some doubt regarding class data member accessing in another file.Follwing code showing error.
class A://file a.cpp
{
public:
int add;
int sub;
};
//file b.cpp
extern class A
void cal()
{
A::add=A::sub;
}
How can I access the virtual base class? This is a practice exercise from c++ primer plus 6.
The problem is that the name becomes No Name instead of the name specified when creating the gunslinger, I don't know how I can call the virtual base class explicitly
Output,
#ifndef PERSON_H_
#define PERSON_H_
#include <string>
#include <iostream>
#include <cstdlib>
using std::string;
class person
[code]....
I have a big problem with searching a solution for getting access on getters and setters of the derived classes of an interface.
Interface:
class IfParam
{
public:
IfParam();
};
Now I have a derived class for each needed datatype. E.g.
class Int32Param: public IfParam
{
public:
Int32Param();
Int32Param(IfParam* l_param);
int getValue();
void setValue(int l_value);
private:
[Code]...
My Problem now ist getting access to the getters/setters over the interface. I wish I could initialize the Params like this:
IfParam* param = new Int32Param();
param.setValue(12);
IfParam* param = new StringParam();
param.setValue("String");
But to have access to the getter/setter I have to declaire the functions in the interface as generic functions. But how? I tried to use temlates, but then i have to declaire IfParam as IfParam<int>. Thats a problem because in my original program I do not know which TypeParam the IfParam interface will be initialized with when I create the pointer.
Basically am trying to reference a method in a my Form1 class into another class. So far I have tried multiple different methods to try and access the method but have not managed it so far. Both classes use the same namespace. The part of my form class that I am using are as follows:
public class Form1 : Form
{
IContainer components = null;
private ButtonPanelThread p1, p3, p4;
[Code]....
how would i access the list created,i should be able to access the list from all other class, adding to it update ect ect.
class test2
{
public string FirstName{ set; get; }
public string LastName { set; get; }
public string Location{ set; get; }
private List<test2> myList = new List<test2>();
public override string ToString()
[code]....
now in a seperate class how would i view the item (print in console) and edit 'mike' location to XYZ.
It's hard to give a precise title but here is the question in detail: I have a class, something like this:
Code:
class classA{
public:
void fnA();
...
};
and another class that contains objects of classA:
Code:
class classB{
public:
classA A1;
classA A2;
classA A3;
vector<classA*> vA;
...
};
classB B1;
Now is it possible to access B1.vA from B1.A1.fnA() through some kind of pointer chain like this->parent->vA ? If so
I have a method:
int filetodb(std::wstring szwf, SQLHANDLESTR *h);
I want to use it, in a thread.
std says, use thread, as:
std::thread second (bar,0); // spawn new thread that calls bar(0)
How can I do this, for my method, that uses more than one, i.e., two, parameters?
My code is:
std::thread thread = std::thread(filetodb, filesP->at(i), h);
compiler says:
Error10error C2248: 'std::thread::thread' : cannot access private member declared in class 'std::thread'c:program files (x86)microsoft visual studio 11.0vcincludexmemory06061ConsoleApplicationa
How, can I do this?
Is it possible to pass the vector index '4' to the Height() function without passing it as a parameter of the function.
Basically, I'm trying to eliminate using 4 twice... what I'd LIKE the statement below to look like is this:
gx.Cell[4].Height();
The only way I can figure out how to get it to work is like this...
class grid{
public:
class CELL{
public:
int Height(int index); //returns the height of this cell
[Code] .....
Suppose I make a class, something like having the constructor being invoked first makes sense, I don't have a problem with that. But, how could I limit access to functions until certain functions are called? Perhaps this isn't built into the language so you can't. And maybe this problem never comes up. For example if you have a set() and get() functions, if they are both public functions, there doesn't seem to be a way for the compiler at least now if set() never gets called you shouldn't call get(). I just see this as error prone if you need to use libraries, you have to know not to do it from documentation instead of something the compiler can check.
View 11 Replies View Related I am doing C++ data structures exercises, and I am still learning some of the more basic concepts. I have a parent class:
template<class T>
class linkedListType {
public:
protected:
int count;
nodeType<T> *first;
nodeType<T> *last;
private:
};
Derived class:
#include "linkedListType.h"
template<class T>
class orderedLinkedList: public linkedListType<T> {
public:
void mergeList(orderedLinkedList<T> &list1, orderedLinkedList<t> &list2) {
first = list1.first;
...
} private:
};
There is more code in my mergeList() function, but I included the line that is giving me problems. The error that my CodeBlocks compiler is giving me is that 'first' was not declared in this scope.
Strangely enough, if I change it to this->first, the error disappears.
1. Why does it not recognise 'first'?
2. Why would this->first work at all? Is the 'this' object a smart pointer?
I need to set signal handler for my process. As the signal is related with the process on system level I have faced the problem. My program consists several classes. They are connected together. But it doesn't metter in this case. The problem is that I need to access to member and methods of the class from my signal handler. For instance , I have class named Foo at it has some members and methods.
So from my handler I need to call its function and change members. I understand that compiler should know that this class instances will exist during all program execution. I have tried to set static member class Foo instance in another class , but this didn't solve the problem. How to correctly implement signal handling in such case.
Here is example of my code
class MyContainer {
private:
std::vector<Foo> container;
public:
int removeFromContainer(Foo* aFoo) {
[Code] ....
I have written a class "FileSet " in program's Document class.
This class contains other Four classes as
"Machine1" , "Machine2", "Machine 3" and "Machine 4".
Now my problem is Machine 1 can not access variables from Document class or other variables from FileSet.
How to access them ?
I was writing generic class Array (based on counting access to elements)and i got compiling error I cannot even understand (in vs2012).
Code: [URL] ....
Error: [URL] ....
When I put boost::thread Thread; in my struct I get the error error C2248: 'boost::thread::thread' : cannot access private member declared in class 'boost::thread'
The whole struct is
struct Player {
bool key[256];
char nameString[64];
bool lMouseButton;
bool rMouseButton;
double mouseX;
double mouseY;
[Code] ....
I have `MainShop`(base class) then `SwordShop` and `BowShop`(derived classes) and another derived class called `Inventory`. I have a vector under protected in my base class, and when I access it from my derived classes it's okay, but each one has its own value. How can I set them all to have the same value?
//MainShop.h
#pragma once
class MainShop {
private:
//some variables
protected:
vector <string> WeaponInventory;
[code]......
Here every time I run it, it goes straight to the `else` and it displays that I do not have any items. I want to just have one vector for both my bow and Sword shops because vectors take up a lot of memory and my teacher said keep them to a minimum. So I just want one vector that takes in items from my bow class as well as my sword class, but for some reason it's acting as if I have multiple vectors, each with its own set of items.
I am currently doing the assignment about linked list. Here are some details information about what I am doing.. This program is C++ and should run on Visual Studio 2010. And it contains three file, two datastructure header and one main cpp file.
This program is trying to arrange and show some sports records. The main program which contain the functions such as reading the result text file(each result text file contain several records of athletes), removing a file, arranging the totalresult and printing it out. And the main program is already given and I cannot overwrite it.
But when I finished and try to build the solution and run it, I am not able to run the program and it give me somethings like these...
warning C4172: returning address of local variable or temporary
error C2248: 'Datastructure1::Datastructure1' : cannot access private member declared in class 'Datastructure1'
see declaration of 'Datastructure1::Datastructure1'
see declaration of 'Datastructure1'
This diagnostic occurred in the compiler generated function 'Result::Result(const Result &)'
And I have tried to comment each function part of the header file and see if can run or not. But I still fail to do so. Here are my codes...
#ifndef DATASTRUCTURE1_H
#define DATASTRUCTURE1_H
class Datastructure1 {
Public:
Datastructure1( );
[Code] ....
There are two header files and look quite long. They are all some linked list functions . I have read and learn linked list data structure before I complete this programs. However, when I complete the functions required, the function cannot be compile....