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?
i have the following error defines.h:14:23: error: two or more data types in declaration specifiers, the begining define.h source code is (the line 14 is in red):
Code:
/* $Id: defines.h 3492 2011-09-18 20:44:09Z nekral-guest $ */
/* some useful defines */
#ifndef _DEFINES_H_
#define _DEFINES_H_
[Code]....
I am trying to create a few subclasses which all use the base class constructor, according to my book this is all fine and dandy by using the "using Baseclass::Baseclass", this doesnt work for me.
class Monster {
public:
Monster(char[], char[], char[], int); //The constructor, and its implemented.
etc..
};
[Code] ....
Yet, i recieve this error:
error LNK2019: unresolved external symbol "public: __thiscall Human::Human(char * const,char * const,char * const,int)"
Why is this? Does doing it this way create const pointers somehow? The constructor works fine with Monster, i am using the same calls, just changed to create Human instead of Monster. All files are included where they should, monster and human are declared in the same header.
Write a program using all storage class specifiers?
View 2 Replies View RelatedIs it possible to apply Print Conversion Specifiers to a single value multiple .
simply put ,
printf("%.1s%6lf
", perimeter_Circle);
I want one digit precision and 7 tab space on this item.
I am trying to copy files, but the windows + compiler gods will not submit easily today. In my code below I get the sysdirectory + the file I want to copy with:
GetSystemDirectory(sysdirect, sizeof(sysdirect)); //Sets system directory IE. C:WindowsSystem32
GetModuleFileName(GetModuleHandle(NULL), cfilename, sizeof(cfilename));
_splitpath(cfilename, NULL, NULL, fileName, extension); //splits the path name up into different pieces
_snprintf(rfilename, sizeof(rfilename), "%s%s", fileName, extension); // writes formatted data to a string
Then
if (strstr(cfilename, sysdirect) == NULL) { //returns a pointer to the first occurence of str2 in str1
char tmpfilename[MAX_PATH]; sprintf(tmpfilename, "%s\%s", sysdirect, filename);
cout << tmpfilename << endl;
[Code] ....
my tmpfilename prints exactly where I want it to go and my debug prints out an error 5 which is an access denied error. I was looking at the system("copy") function, but I don't think I would be able to use my pathnames. From what it looks like I would have to hardcode in like "copy C:windowssystem32".
When I am giving elements for row 2 ,program crashes .it says access violation.
Code:
#include<iostream>
#include<vector>
#include<string>
using namespace std;
void matrix_init(vector<vector<string>>& v)
[Code] ....
My goal is accessing c++ objects within c by using wrapper and externals. To get the pointer to the c++ object I use a type "void *".
But i get an error while linking: undefined reference to "create_mycpp".
Should I take an other way to access c++ objects?
Code:
//-------------------------------------
//mycpp.cpp
#include "mycpp.h"
Mycpp::void func(int i)
{
i += 1;
[Code] ....
I have a crash on a application the customer machine i couldn't reproduce it yet on my machine... all i have is the error message
The Instruction 0x0070478b referencing to the memory 0x00000000 could not be written.
And that's all i have how do i track that instruction on my program from that address? is it possible?
private void update_Click(object sender, EventArgs e) {
OleDbConnection conn = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;
Data Source=C:UsersshobhitDocumentsEnvironment_Monitoring.accdb;
Jet OLEDB:Database Password=divya6");
String sdat = dateTimePicker1.Value.ToShortDateString();
String la = labs.SelectedItem.ToString();
[Code] ....
Here is my code so far, the problem is when I debug it I keep getting the same error but everything seems to be correct.
The error is: Unhandled exception at 0x00ED8F34 in ENCDEC.exe: 0xC0000005: Access violation reading location 0x00000008.
#include <iostream>
#include <fstream>
#include <string>
#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <ctype.h>
using namespace std;
char buffer[100];
class cSecret{
[Code] .....
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.
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.
View 3 Replies View RelatedI 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] .....
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?
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?
#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?
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 ?
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?
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.
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.
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];
Not inheriting properly and provide the corrected code if possible
Code:
#include <iostream>
using namespace std;
class Node {
protected:
int Data;
[Code] ....
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{
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?
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?
