C++ :: Array Of Class Objects
May 13, 2014
I need an array of class objects but am unsure of how one might accomplish this. I have so far...
//element class driver code
Element Arsenic(lowCeiling, highCeiling);
Element Cadmium(lowCeiling, highCeiling);
Element Chromium(lowCeiling, highCeiling);
Element Copper(lowCeiling, highCeiling);
Element Lead(lowCeiling, highCeiling);
Element Nickel(lowCeiling, highCeiling);
Element Molybdenum(lowCeiling, highCeiling);
Element Mercury(lowCeiling, highCeiling);
Element Selenium(lowCeiling, highCeiling);
Element Zinc(lowCeiling, highCeiling);
Element metal[10] = {Arsenic, Cadmium, Chromium, Copper, Lead, Nickel, Molybdenum, Mercury, Selenium, Zinc};
Could the array be created in this manner or is that illegal code?
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Mar 21, 2015
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?
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Jan 16, 2013
Please consider the following code :
#include <iostream>
using namespace std;
class superclass;
class subclass1;
class subclass2;
[Code] ....
As you can see I want to create a dynamically allocated storage of references to a parent class each of which can then point to a child class, how ever I do not know how to extract the child class out again from that array so i may access its variable b.
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Oct 12, 2014
class FlashCard {
public:
int a,b;
void PrintCard(void);
int CorrectAnswer(void);
};
void SwapFlashCard(FlashCard &a,FlashCard &b)
[Code]....
Why does Xode warn me that Type'FlashCard'does not provide a subscript operator on line 22,23,29 and 30?
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Jun 26, 2013
What I want to do is have an admin class which will hold all the employee objects, can add them, list and calculate salaries. I'm trying to make array of objects, not sure if it's right
here is the code
Code: #include <iostream>
#include <string>
using namespace std;
class Employee {
public:
Employee(string name, short type, int salary)
[Code] .....
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Feb 11, 2013
So starting with the Item.h file :
#ifndef ITEMH
#define ITEMH
using namespace std;
class Item
[Code]...
I think I'm getting the wrong idea about strings. I thought I could add data just by using '+=' but apparently not.
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Aug 18, 2013
class A {
Public:
A (int);
A(int,int);
int get (int,int);
};
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Jan 24, 2013
I have written a selection sort algorithm to go sort an array of class objects by age in ascending order, the problem is that the output being given does not match what i think the code should do. when the program runs the 3 records are added to the array and when they are sorted should be outputed in ascending order, the problem is that with my code the last 2 are sorted properly but the first element does not seem to move, it remains the same as the original unsorted value.
My code for the selection sort function and the display method are below:
void selectionSort() {
int i, minIndex, minValue;
for (i = 0; i < (arrlength - 1); i++) {
minIndex = i ;
[Code].....
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Jan 22, 2013
I have a linear search algorithm set up to search through an array of class objects it works but the output does not match, when i search for a particluar name in the array the 1st and third values int the array are found but the second value is not found..
below is my code:
int linsearch(string val) {
for (int j=0; j <= 3; j++) {
if (player[j].getLastName()==val)
return j ;
[Code] .....
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Jan 6, 2015
Let's say I have a Car object , and it contains inner Engine object.
Code:
struct Car{
Engine mEngine;
};
In order to initialize the engine object NOT by the default constructor (if it has any) , we use initialization semantics:
Code:
Car::Car:
mEngin(arg1,arg2,...)
{
other stuff here
}
Now it gets tricky: Let's say a Car objects has 10 inner objects, each object has about 5 variables in it . Car is a base class for , e.g. , Toyota class. you don't want the Car class to have a constructor with 50 arguments. Can the inner objects of Car be initialized from the base class , e.g. Toyota?
Code:
class Toyota:
Car(...),
mEngine(...),
mGear(..)
{
...
};
The other options are:
1) like said , create a Car constructor which gets 50 arguments, then initialize Car as whole from Toyota - the code becomes less readable and less intuitive
2) Car constructor which get built-objects as arguments and initialize the inner objects with copy constructor . the code gets more readable but then you create many excess objects .
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Apr 9, 2014
I have been working on an assignment where I have to add three objects of a class Matrix. The class should have the flexibility to add more than two oprands without changing any operand on Left hand side of the '=' operator.
Matrix obj1, obj2, obj3, obj4
Obj1=obj2+obj3+obj4
I am using the following code for this
Matrix Matrix::operator + (Matrix &obj) {
if((this->Columns == obj.Columns) && (this->Rows == obj.Rows)) {
for(int i=0;i<obj.Rows;i++)
[Code] .....
the problem is that it is just adding only 2 operands. How can I add more?
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Mar 16, 2013
So I'm trying to store class objects in a vector:
#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
[Code]....
1. Am I storing it correctly?
2. How would I access the stored data, say, if I wanted to compare it to other stored data or COUT it?
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Mar 22, 2013
For a beginners C++ lab, I have a base class Employee and two derived classes HourlyEmployee and SalaryEmployee. In main, I have a vector defined as vector <Employee *> VEmp; It's then passed to a function to get the input, which works fine. But what I'm struggling with is another function with the header "printList(const vector <Employee *> & Ve)". It's supposed to loop through the vector and call the appropriate printPay function, which is a seperate print function inside each derived class. How do I loop through the vector and print it out? I was trying to do a for loop and something like "Ve[i].printPay();", but that doesn't work. So how would I do it?
Here's some snippets of the relevant code.
class Employee {
....
virtual void printPay() = 0;
};
class HourlyEmployee : public Employee {
[Code] ....
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Aug 23, 2014
For example when I have:
Class A{
B objectB;
};
Now when I instantiate the object of class A like:
main(){
A objectA;//option 1
A* pObjectA = new A();// option2
}
How is objectB stored in memory (stack heap etc.) for both options??
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Feb 17, 2013
i ran the following code in the latest version of code::blocks and it tells me that the objects cout and cin are not declared in this scope. what is the problem?
I used to use Turbo C++ 3.0 and i had no problem whatsoever with that compiler. But now i am trying to move to code::blocks but it is proving very very hard as all the standards have been changed.
I am a school student and thus, we had been told to practice on Turbo C++ 3.0 and now i am unable to unlearn it. Also, if i use printf in place of cout there is no error but i want to use cout as it is what i am comfortable working with.
#include<fstream>
#include<conio.h>
int main() {
using namespace std;
char name[20];
[Code] ....
Is there some document to which i can refer so as to get the latest C++ standards which is C++0x i believe?
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Jul 8, 2013
Is dere is any limit in number of objects of a class?
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Oct 13, 2013
I am working on a project that requires me to create objects from a abstract class that has 2 child classes (that need to be derived). Any examples on how to do this? I looked online and the examples were pretty vague. the main error that I am getting is when I make a temp object with & in front of it (such as Employee &genericEmp) it throws a must be initialized error.
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May 27, 2013
Running into a snag in my program. I can't seem to figure out how to have an object of a class be able to look at all the other objects of its own class.
Reasoning being, I'm working on a game with multiple ships flying around in the same space. Each ship is a class.
Each ship has an x and a y, and needs to compare the angle and distance of other ships' x and y coordinates to see if they're visible on the same screen.
How to tell an object to look at objects of its own class.
Here's some code:
common.h
#ifndef COMMON_H_INCLUDED
#define COMMON_H_INCLUDED
int dist(int x1, int y1, int x2, int y2);
int get_info(int which);
[Code] ....
Basically, I just don't know how to properly write a function, call, or how to get the info I need, to the Player::get_closest() function so that it can see the other play objects.
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Nov 3, 2013
regarding dynamic vector.
Shape2DLink.cpp
void Shape2DLink::InputSensor()
{
string shape,type;
[Code]....
So i'm actually using polyphormism for calculating the area of the cross and other shapes. so how do I actually make use of dynamically create an object this way?
do I create them in my Shape2DLink or in my individual child classes?
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Dec 9, 2013
I'm having the same problem : [URL] .....
Though, my vector isn't one of int, it is a vector of objects from another class and NetBeans won't compile it.
#include <cstdlib>
#include<vector>
#include <string>
#include<iostream>
using namespace std;
class estoque{
[Code] .....
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Feb 13, 2013
I am trying to add matrices a and b. I am getting an error in the "add" function, probably because I have m[i] in it, and m is not an array. What is the correct way of writing the "add" member function here?
Also, although the "read" and "write" member functions of the class are working just fine, do you think there is a better way of writing them?
Code:
#include <iostream>
#include <cmath>
#include <iomanip>
using namespace std;
const int rows=3;
const int columns=3;
[code].....
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May 7, 2013
I am new to C++ programming and i have a small assignment.
How to implement a thread safe class to manage a queue of objects. Accessing the front of the queue should be a blocking operation when the queue is empty.
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Aug 18, 2013
I've a text file : Random.txt which comprises of
Jade
12MS234
Male
18
Rocky
12MS324
Male
18
Marx
12MS632
Male
18
Now in my program i've a class
class stud
{
char name[10];
char reg[10];
char gender[10];
int age;
};
Now I've to write a code in c++, where i've to read the given data and store this into 3 objects of stud class(array of objects) ...then further i've to manipulate the above stored data. I think i'm getting error while storing...variables are showing random characters... give me the code.for this program..in C++
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Jun 20, 2013
I am having difficulty with class objects.
1. why my program won't actually compare the two strings.
2. why and where I am having a memory dump crash.
The following is my main.cpp, String.cpp, and the header file in that order.
#include <iostream>
using namespace std;
#include "GREEN_String.h"
void main () {
GREEN_StringStr1;
GREEN_StringStr2 ("AdrianGreen");
[Code] .....
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Dec 3, 2014
I am working on a video game that is based on a tutorial I found online and I ran into an issue associated with accessing an object's method inside another class object's function without making the object global which seems bad.
Here is basically how the tutorial set things up in the game: The game has a base class called GameObject then there are other child classes that inherit from this class. The GameObject class has all the basic information an object would have that needs rendered on the screen (x/y position, size of bitmap, bitmap, whether or not it is collidable, etc).
One of the child classes SpaceShip, which is the player so it has attributes and methods associated with managing # of lives and points scored.
There are other child classes of GameObjects in the game that need to take life and add points from the SpaceShip object if they collide with the spaceship or other objects.
In the collision handling routine I basically call a function "void Collided(int objectID)" when a game object collides with another. Within the Collided() routine, there is logic that executes code or other functions based on the objectID it collided with. Some of the collisions require taking life from the spaceship or adding points. The way this was accomplished in the tutorial was with function pointers (see Bullet class constructor and collided method for example). Is this really the best way to handle this sort of thing? It seems like there has to be a simpler way than to keep referencing function pointers in any new class I want to add to the game. I realized this when I went to add a method for the spaceship to fire bullets rather than inside my game class.
My Project Source found here: [URL] .....
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Apr 28, 2015
We are coding a Blackjack/21 game. I have a Deck.cpp class, Deck.h, Play.cpp (holds Main), and Card.h (holds card struct). I also have a Hand class/header, but I'm not using it yet. This is what is required per instructor.I am having issues accessing the functions that are in my Deck class. I have tried a few other means to access the class's function, but I've already gotten rid of those. These three are my latest attempts with the specific errors in the comment on the line the error was happening.
ve.
Here is my Deck.h
#pragma once
#include <iostream>
#include <fstream>
#include <string>
#include <cstdlib>
#include <ctime>
#include <iomanip>
#include "Card.h"
#include "Hand.h"
using namespace std;
class Deck
[Code]...
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