C# :: Inheritance In WinForm Design
Feb 23, 2014
I have two Form Employee and Instructor, here Employee is super class of instructor.
public class Instructor: Employee
{
//Instructor class
}
I am able to access all property of Employee inside instructor class but with these some textbox and button design inside Employee design is also getting inherited inside Instructor design and i don want this and i want to maintain the parent-child relationship between Employee and Instructor.
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Feb 27, 2014
1.I wanted to create my own title bar in winform.
2.I have created for one form and i want to apply it for all form.
3.Are there any Styling winform package available for free.
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Jul 29, 2014
So basically, I started out with each wizard == 1 winform, but then I found another way to do it by making the content of each wizard step a user control, then say, on initial deployment, it load usercontrol1, then when i click next, the panel hide usercontrol1 for usercontrol2 and so forth. Would it be feasible to create all usercontrols (all the wizard step) and add them in an array, then i can load them by index?
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Nov 12, 2014
So I am upgrading the system from 3.5 .NET to 4.5.1 and fixing any bug that I could find. Long story short, I run into an issue that basically tell me it couldn't find the images in the resource file. I figured out a work around, but first I have to set the picture box or background Image in design time to none. I ran into this Properties Windows while changing the value of picturebox for my user control saying: Property value is not valid. Object reference not set to an instance of an object. This usercontrol is taken from another user control from a different project. Basically, we are reusing it.
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Jun 18, 2014
I have a main WinForm that I want to press a hotkey and show and hide the form. I can press Insert and hide the form and I see its icon in my Win7 task bar but when I press Insert again it doesn't show. Is my coding logic wrong to make it work? Maybe when its hidden the Insert key isn't being 'seen'? Although the code I am using I got somewhere on the internet that says it will work at the app level.
virtual bool PreFilterMessage(Message% m) {
// Detect key down messages.
if (m.Msg == WM_KEYDOWN) {
Keys keyCode = (Keys)((int)m.WParam) & Keys::KeyCode;
[Code] ....
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Jun 18, 2014
I made a winForm with a button on it in the Designer (VS 2010 C++).
But when I run my app, the button does not show on the form.
The button visible property is set to true.
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Nov 11, 2014
I have the following code. I have hardcoded the x and y values to test. And for some reason for the point (0,-0.5) it plots (1,-0.5) . What is going on, because if you try other values then the graph displays correctly.
foreach (var grp in q) {
point = new DataPoint();
Sum1 = grp.Sum1 > 2 ? 2 : grp.Sum1;
Sum1 = Sum1 < -2 ? -2 : Sum1;
[Code] ....
Attached is what is displayed.
Attached image(s)
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Dec 24, 2012
How do I count the objects(for example botton) on the form
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Aug 20, 2013
I was created winform application with sql data base, after i created it i was converted to the installer file,for the other users but when they run the application did not connect to the database, how i fix this stuff...?
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Sep 5, 2013
i have read that inheritance slows down the process.because a_class -> b_class -> c_class it goes thorough many classes to find a function or a value. people advices not to do it more than a few times. what if instead of inheritance we are using headers, would it slow down the process also??i mean which one is faster? and arent both the same when we use headers or used inheritance.
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Jan 17, 2014
I want to define a base class A which allows different type of logging (file stream, console, etc). In the meantime, I want a class B to to be able to call A's print function (i.e. derived class C's print function which defines the logging method). However, I don't want to make A's print function to be public because it will only be called by B.
class A {
protected:
virtual void print(void);
};
[Code] .....
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Feb 19, 2014
How to put virtual keyword in the function of the base class. Will the function still be over-written properly? What will happen if I
(1) call function from base class pointer
(2) call function from derived class pointer
(3) call function from derived class object
If the virtual keyword is present, the over-written version will be called in all cases, am I mistaken?
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Feb 18, 2015
I have 2 classes with a Function with the same definition (both inherited from the same base class) and in my derived class I derive from both of those 2. Is it possible to use the Methods of both classes? for example with an other name?
class A {
protected:
int print(int a) { std::cout << "int A: " << a << std::endl; }
};
class B : A
[Code] ....
is there something like using C::print as printc;?
The Problem, I have a Sprite class that derives from a Rectangle with properties Position, Size, Origin and Angle and a Text class that derives from Rectangle. Now i have a Button class deriving from both Sprite and Text.
- The Position, when moving the Button i have to change the position of both so i Implemented a new Method which calls SetPosition from the Sprite and the Text.
- The SetSize just affects the Button so i just did using Sprite::SetSize;
- The angle affects both so i just implemented a new Method and hide the other two
The problem is here:
- The Origin: writing button.SetOrigin(-1,0) should set the Origin of the Button and writing button.SetTextOrigin should set the Origin of the text.
Should i just reimplement a Mehtod named SetTextOrigin and call Text::SetOrigin from there and hide the button.Text::SetOrigin or is there something like using Text::SetOrigin as SetTextOrigin?
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May 16, 2013
#include <iostream>
using std::cout;
using std::endl;
class CBox // Base class definition
{
public:
// Base class constructor
explicit CBox(double lv = 1.0, double wv = 1.0, double hv = 1.0) : m_Length(lv), m_Width(wv), m_Height(hv)
[Code] .....
This example produces the following output:
// Derived class copy constructor
CCandyBox(const CCandyBox& initCB): CBox(initCB) {
std::cout << std::endl << "CCandyBox copy constructor called";
// Get new memory
m_Contents = new char[ strlen(initCB.m_Contents) + 1 ];
// Copy string
strcpy_s(m_Contents, strlen(initCB.m_Contents) + 1, initCB.m_Contents);
}
It will work right? Cause when I do "CBox(initCB)" it only sends the BASE part of the derived object to the base class copy constructor, is it copy or default?
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Dec 20, 2013
I have Class A as a base class , and Class B , C derived classes from A and there's class D who have a data member (pointer to Array) of type A (Composition)
class D{
A **a;
int size;
.......
a = new A*[size];
......
};
And i have Print method , in its body i have to specific element (if it from class B or C ) with a given ID(both B and C have a data member ID ) there should be 2 options in print function .. printing elements for class B , or printing elements for class C ? how can i specific the elements ?
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Oct 20, 2014
I have been reading up about object oriented programming recently and have come across 'Encapsulation, Polymorphism and Inheritance' as i understand it so far all OOP programs should use these three concepts. So i started thinking how do i get these concepts into my program as i am using WPF C# and i could not really find much good info about how these concepts apply to WPF programs.
Or do these concepts just not work with WPF programs?
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May 27, 2013
I'm writing a bunch of classes like Form, Button, etc. All these are derived from a base Object class. I want to make these objects auto-delete, so I only have to declare the new keyword, and the program will clean them when necessary. I understand the implications of dereferencing, I just have a couple of questions about my code.
I through this run-down example together:
Code:
#include <Windows.h>
#include <map>
class Object {
public:
Object() {};
~Object() {};
void *operator new(size_t size);
void operator delete(void *ptr);
[Code] .....
I have added a static variable of std::map type called m_Dynamic. I have overloaded the new and delete keywords (within the Object class) to keep the m_Dynamic map up-to-date. This prevents objects created on the stack from being deleted.
The object itself can then be deleted via the base Dispose() method. Or methods such as Destroy() can be added in derived classes and call upon Object::Dispose() themselves. This can be overloaded, etc, but eventually will be removed from the public view. I only have it here for testing.
From what I can tell everything "works", though I'm uncertain that the object is being correctly deleted.
Though, my main concern is that when a derived class such as Circle calls Dispose() which in turns fires delete this. Does it free() the sizeof(Object) or does it correctly free() the sizeof(Circle)?
Are there any other things I should be vary of? I only just started playing with new/delete overloading yesterday.
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Jun 6, 2012
Shape base class, line and Point derived classes. What should I declare in .h files and implement in .cpp files that this is array will be work.
My major concern refer to operator [] and assign (=) operator. As far as I understand I should overload ([]) and (=) three times for classes shape , line and point or not... or is it possible made through virtual function? How will be code looks like ?
Code:
// part of main.cpp
Shape* shapes[3]; // Array of pointers to Shape
shapes[0] = new Shape();
shapes[1] = new Line ("line from array ", Point(1,22),Point(33,22));
shapes[2] = new Point(11,44);
cout << "using ToString function" << endl;
for(int i=0; i < 3; i++)
cout << s[i]->ToString();
for(i=0; i < 3; i++)
delete s[i];
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Aug 5, 2013
let me show you the (simple) code:
Code:
#ifndef DUCK_H_
#define DUCK_H_
#include<iostream>
using namespace std;
class Duck
[Code].....
When I compile, it says: "error: 'virtual void Duck::display()' is protected" how come I can't gain access to MallardDuck's display(), which is public?
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Jan 5, 2014
Not inheriting properly and provide the corrected code if possible
Code:
#include <iostream>
using namespace std;
class Node {
protected:
int Data;
[Code] ....
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Feb 18, 2015
I am having some serious issues with class inheritance. I am trying to make a MoneyBag class inherit from a class called bag. This will not work. I get an error complaining: error: expected class-name before '{' token. And yes I have googleing it and tried several of the various solutions offered with no avail.
The MoneyBag is pretty simple right now as I wanted to get it connected to bag before I tried to do anything with it.
//MoneyBag.h//
#ifndef MONEYBAG_H
#define MONEYBAG_H
#include <bag.h>
class MoneyBag : public bag{ ////<<------ Error appears on this line.
[Code] ....
So based on everything I have seen on line the statement:
class MoneyBag : public bag{ is legal.
As it is done this way on this very site's tutorial:
class Rectangle: public Shape, public PaintCost{
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Sep 16, 2013
Code mostly speaks for itself:
#include <list>
#include <iostream>
using namespace std;
[Code]....
I added an object of class myderiv to the container, but when I retrieve it back and try to manipulate it, it's actually of class mybase. Is there any way to keep the inheritance information in the container?
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Sep 16, 2014
I have couple of objects which are using some amount of methods. Right now my application is not OOP and i am going to transfer it to OOP. So i would create each class for my each object. Almost all methods are in use for each object, the only one thing which is changing some of those objects passing not all parameters inside specific method. I can go two ways one is prepare interface for all methods i got and each of my classes could implement its own definition for it but other way almost all would implement exactly the same methods but with different parameters so maybe its better to create base class then for each object do inheritance from base class (polymorphism). inside base class i can prepare base methods and classes which will inherit from that class would override those methods for requirements they want.
So imagine: You got:
Memory
CPU
Latency
and all of them using mostly all of those same methods (only arguments for one of them could be use different way):
ExecuteQuery()
ExportToExcel()
PopulateDataTable()
PutValueToReport()
Now its better to do like this e.g:
Base class: Stuff
prop: name, id, date ...
methods to ovveride: ExecuteQuery(), ExportToExcel() ...
classes: CPU, Memory, Latency (inheriting from Stuff)
ovveride methods and align its definition for specific class use (remember mostly only passing args are used or not by specific class)
or go with inheritance
Interface SomeMethods
ExecuteQuery()
ExportToExcel()
PopulateDataTable()
PutValueToReport()
and each class would implemet its own definition.
The most important thing is that those every objects mostly using all of those methods and what is diffrence that one object can use all of available parameters inside this method and other one no. What i should do? Go with interface or inheritance and polymporfizm inside base class?
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Jun 20, 2013
Here is the code:
class Foo {
public:
Foo(){cout<<"Foo"<<endl;}
};
class Bar : public virtual Foo {
[Code] ....
This is a typical implementation of multiple inheritance. If define class FooTooBar as,
Code:
class FooTooBar : public virtual FooToo, public virtual Bar {
public:
FooTooBar(){cout<<"FooTooBar"<<endl;}
};
I know why we use virtual inheritance in the class Bar and class FooToo. But if we use virtual inheritance in the class FooTooBar, does it make any sense?
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Dec 17, 2014
Write a program using inheritance allow user to enter grades of his students 5~8 students as a base class and compute the sums for each students in derived class and compute the average of sums in another derived class. I created 3 classes in 1 header file and 1 cpp file how ever i cant seem to get the sum or the average to show up on execution time
header file
#ifndef GRADES_H_INCLUDED
#define GRADES_H_INCLUDED
class Grades {
public:
Grades()
[Code] .....
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Sep 19, 2014
I've been working on a program that uses a reference counting class that I've written which works fine for objects that inherit from it however I now need to have the following setup:
class SBComponent : private Refcounted { /*stuff*/}
class ProxiedComponent : public SBComponent, private Refcounted {/*stuff*/}
The compiler gives the following warnings
warning: direct base ‘Refcounted’ inaccessible in ‘ProxiedComponent’ due to ambiguity
And then several repeats of the error:
error: request for member ‘bk’ is ambiguous
Back *b = bk<ProxiedComponent>();
bk is a templated function that's defined in Refcounted and returns a pointer of type <template arg>::Back (ProxiedComponent::Back in this case).
I don't understand why the call to bk is ambiguous as although there's two instances of Refcounted (there needs to be with the way I've designed it so I can't make it virtual) it's inheritance is private in both cases so there should only be one instance of it visible in ProxiedComponent.
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