I just wondering if there's a way in C++ to get classes dynamically which have the same base class? I mean, instead of creating switch statement to create multiple classes, I would like to use a single line to create any of these classes.
//Instead of:
switch(class_type) {
case type_1:
SubClass_1 obj = new SubClass_1();
[code].....
I'm having problems with this code:
#include <iostream>
using namespace std;
class Foo {
public:
Foo( int n );// Constructor
~Foo();// Destructor
int *ptr;
int N;
[Code] ....
I'm using Visual C++ 2008 version. The problem arises at the end, after the sentence 'system("pause")' is reached, which makes me think that the problem happens when calling the destructor. The destructor is called twice, the first time it's called is in the function print. The problem seems to be that the destructor can only be called once.
I know I can avoid this situation by defining the function print like this:
void print ( const Foo &f )
...
but I would like to know if there is some way I can do this keeping the definition that I've provided.
Class with Pointers and Dynamic Arrays
View 2 Replies View RelatedI have become overwhelmed an frustrated at these current operator overloads!
Currently I still can not get my +,* or istream operators working at all!
#include <iostream>
#include <cstring>
#include "myint.h"
[Code]....
I want to allocate dynamically classes from a table. There is a different number of class derived from the same father class. Actually I do:
Code:
typedef struct sSysFBList {
TCHAR name[64];
int dim;
SystemFB *fbExec;
}systemFBCalls;
[Code] ....
and so on. NOTE: SystemFB is the virtual father class, all the other are derived from it.
I would like to know if there is the possibility to define the type of the class in the systemFBCalls struct to avoid all these if - else if - else if
Code:
typedef struct sSysFBList {
TCHAR name[64];
int dim;
????? name_of_class;
SystemFB *fbExec;
[Code] .....
How do I copy from a dynamic array initialized in a class but with a different memory address. For example if my array is a dynamic array initialized in a class...
Code:
const int CAPACITY=5;
class Array{
public:
Array();//constructor
[Code] .....
How would i copy this array to a another array but have a different memory address so when i deallocate array a my copy array also isn't deallocated.
// dynamic memory for 2D char array
char **board = (char**) calloc(column, sizeof(char*));
for(int i=0; i<column; i++)
board[i] = (char*) calloc(row, sizeof(char));
//for char 255 row and colum
char temp[255];
inputFile.getline(temp,255);
[Code]...
so i want to change into vector class like Vector<board>row;
I'm writing a class that has two constructors. However, I can't get them to work quite right. One constructor has a parameter of an int (with a default value of 0) and the other has a parameter of a C-style string.
First of all, are these function prototypes correct for the constructors?
MyInt(int n = 0);// first constructor, int param, default value 0
MyInt(const char * c);// second constructor, c-style string param
Both constructors work fine in some cases but don't work in all cases. Here are some potential calls to these functions that are supposed to work:
// These two work fine
MyInt x(12345),
y("9876543210123456789"),
// The array assignment doesn't work when the value is negative
// I'm not allowing negative numbers, but I want to create the object and assign the array to 0
r1(-1000),
[Code] .....
Here's the private data from the class (from the header file):
private:
int currentSize,
maxSize;
char* digits;// Pointer to an array of digits
// Increase the size of digits array by 5
void Grow ();
I attempted to create a dynamic array class for use in my engine (due to problems regarding a dll-interface with the standard library), so I tried at making a standard-compatible allocator template class first. After I "finished" that, I went on to work on the dynamic array class itself.So I finish the dynamic array class, and test it with the standard allocator. It works perfectly, but when I test it with my custom allocator class, it fails terribly.
To make sure it wasn't my DynamicArray class that was causing issues, I tried using the custom allocator on the std::vector class template, and it didn't work either. IMy DynamicArray class code:
// Represents a dynamic array, similar to the standard library's "vector" class.
template<typename T, typename A>
class DynamicArray
{
public:
DynamicArray() :
data(nullptr),
elements(0),
capacity(0)
[code].....
The "Request" and "Free" functions are my engine's equivalent of malloc and free (or new and delete). I allocate a large buffer (16 mb), and through those functions I distribute the memory to where it's needed.
I have a class called Book and I am trying to create a dynamic pointer based array of the class. When I try to run the program I keep getting the error: pointer being freed was not allocated at the line of code that says "delete [] A;". I am using Xcode to run the program.
Book *changeArraySize(Book *A, int &size, double factor) {
int i;
int newsize = size*factor;
Book *A2 = new Book[newsize];
[Code] ....
How I can implement it.
Tickable.h
#include <list>
#ifdef TICKABLE_EXPORTS //Automatically defined by MSVS
#define DLL __declspec(dllexport)
#else
#define DLL __declspec(dllimport)
#pragma comment(lib, "Tickable.lib")
#endif
class DLL Tickable{
[Code] ....
error LNK2001:
unresolved external symbol "private: static class std::list<class Tickable*,SKIPPED BITS> Tickable::subs" HUGE_SYMBOL_LIST
PATHTickable.obj
I know with such a tiny and insignificant class the dll export seems pointless but this class is actually intended to be a .lib ONLY. But it is derived from by .dll style classes, and through inheritance this error is the exact same as what appears in the derived class, I just imagine that the cut down version would be easier to work with.
Is it possible to hold either a static variable in a dll which is of a dynamic type, OR would it be possible to reference an external variable which is static throughout the instances and this variable can be chucked away in a namespace of mine somewhere?
I suppose my only other option (if this is possible) would be to define a maximum instance number and create a standard array of pointers but this could both waste so much memory when not in use and cause problems if I need more memory.
I'm writing a program in which I have to use a matrix to represent a file in code. because it's a file, the size of the matrix is undefined, and therefore the matrix has to be dynamic. I found out that my compiler doesn't like dynamic multidimensional arrays, so I was thinking of this matrix as a dynamic (monodimensional) array of other dynamic (monodimensional) arrays. My program (and thus this example) uses unsigned chars.
unsigned char variable=something;
unsigned char**matrix=new unsigned char*[lenghtOfMainArray];
for(int rowNumber=0;rowNumber<lenghtOfArray;rowNumber++)
{
[Code].....
i'm implementing a playerclass for a game.. in the game there are multiple player types, weapons ect.. i just wanted to turn my players weapons into a dynamically allocated c_str. once i added my: Destructor, Copy Constructor and Overloaded Assignment Operator. My initial values became corrupted and i cannot fix them.
Player2.cpp
#include <string.h>
#include <iostream>
#include <cstdlib>
#include <iostream>
#include "player2.h"
#include "dice.h"
#include "gamespace.h"
[code]....
I am having troubles with dynamic arrays and pointers. All the errors are of that kind. I think when I am assigning malloc to an array we assign to its address.
Code:
/*Create an array of genes of the large matrix*/
gene_t gene,gene1,gene2;
gene=malloc(INITIAL*sizeof(gene2)); Code:
while(...) {
if (gene_num==current_size){
[Code] .....
Code:
Int** d = malloc( ROWS * sizeof(int*));
for (i = 0; i < ROWS; i++)
d[i] = malloc(COLS * sizeof(int));
fx(d);
My question is, in a function declaration, why do I not have to specify the number of columns. How is this different than when I pass a static 2D array to a function, in which I must declare the function parameter with the number of columns.
Code: void fx(int d[][COLS]);
VS.
Code: void fx(int **d);
i just need clarification on if this is what is considered a dynamic list of characters, i don't want a linked list.
Code:
struct dlist {
int size;
int maxsize;
char *datafield;
};
In our homework assignment it states to, "write a set of dynamic linked lists" and so on. Now, the problem I'm confusing myself is at the storage inside of each node. To my understanding, each node contains the prev and next nodes, but also a pointer to the data, in this case being a string. He has asked us to manage these strings as rows of chars such as
char[0] = c // first node being addressed here
char[1] = a
char[2] = t
char[3] =
char[4] = d // second node starting here
char[5] = o
char[6] = g
char[7] =
I have written my code where each node is holding a string, not separated as shown above... my question is to how you can build your doubly linked list where each node is being address a set of chars.
I have declared a global variable as pointer. The program performs certain number of iterations. After every iteration, the size of memory required for the pointer changes and this pointer variable is to be accessed by different functions. Now, here is my doubt:If I allocate the memory for this global variable in a function, will the contents of the memory be lost once I exit that function. In my opinion, it should not be the case as the dynamic memory allocation takes place in "heap" and should not be affected by the call of functions.
View 4 Replies View RelatedCode:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
char * form(char *format, ...);
}
[code]...
So, this is the code i have problem with, as far as i can see, function form actually does the same thing that printf does.It probably puts all of the arguments sent to the function together into one string.
After i set the value in the first structure owners name, i set the cats name equal to it. but when i change the value in the first structure it doesn't change the value in the second structure.
So i need the dogs owners name to be equal to the cats owners name
So if i change the value of the dogs owner it also changes the value of the cats owner.
Code:
#include <stdio.h>#include <stdlib.h>
#include <string.h>
//stucture
struct structDog {
[Code] ....
I am trying to come up with a way to make use of a "multilevel dynamic" container. I am parsing a file to grab some pieces of data. Lets say the first field of data I find I push into an array. At the same time lets I wish to create 2 cascaded sublevels. So an element in Modules is a pointer to the Types vector associated with that module and each element in Types is a pointer to a vector of Data. This concept should be similar to memory paging.
/*
Modules Types Data
____ _____ ______
|____|------> |_____| ---------->|______|
|____| |_____| |______|
|____| |_____| |______|
|____|
|____|
|____| _____ ______
|____|------> |_____|----------->|______|
|____| |_____| |______|
*/
Obviously this becomes very hair quickly so it is obvious that I need to dynamically create and destroy vectors (if I do it this way). Should I just create pointers using the new operator?
Here is some of my code if it is even worthwhile to read:
class Parser {
//storage arrays
vector <string> modules;
vector <string> terminal_type;
vector <string> tag_type;
vector <string> data;
[Code] ....
parse this stuff and nicely organize it.
If you take the first one, "max_logvar" is a module so everything between < and > is associated with that module.
symb is unimportant for now.
then "proterm" is a "module type" so then module now needs a module type container but I may have more than one of those.
so then I break it down by "Input" and "Output" where each of those can have the integer values (just in an array where each position will be set) that are in the fields to the right.
I am new to C++ language and I am still learning.I'm doing basic stuff to better understand dynamic memory. I was wondering why I keep getting memory issues.*/
#define SIZE 15
class word {
char* str;
public:
[code]....
My purpose is to fill a matrix with random numbers. As you can see in the code, I defined a matrix called sim_matrix (which should be filled), but the dimensions of such matrix is given by the parameters that we introduce in the constructor. Because we don't know the size of such matrix until we give these parameters through the constructor. I'd like to know how to declare such matrix, or how to modify the size,...
The header of my file MonteCarlo.h is:
/* MonteCarlo.h */
#ifndef MONTECARLO_H_
#define MONTECARLO_H_
using namespace std;
class MonteCarlo {
public:
MonteCarlo(int n_paths, int n_simulations);
[Code] ......
All entities need to be stored in the dynamic memory. I managed to force this by making the constructor private and by adding a static method which dynamically creates an object and returns a pointer. But it is most likely that the user will want to make them dynamically and we still have the following problem.
entity* player = entity::create();
(*player).setPosition(something);
(*player).act();
(*player).draw();
You get the point, having to dereference the pointer before each call becomes painful. So I thought about this... Instead of returning a pointer, I can return a reference. Then the code is much cleaner.
{
entity& test = entity::create();
// do stuff...
test.act();
// more stuff...
test.destroy(); // deletes the dynamic object
}
I put this code between brackets. That's because we must make sure the reference test doesn't exist after destroy is called, because destroy() makes it invalid. This is fully functional and won't cause any problem as long as the user doesn't forget to never call any method on a destroyed entity. But it's evil code. Would you risk it, or is there another way around?
I remember in C++, when a dynamic array is allocated, the size of this array is stored right before the array in memory. Therefore compiler knows exactly how long, when this array is deleted.
Do all compilers store the size this way? Is it a safe method to get the size of a dynamic array?
Here is a example code, it works fine on Visual Studio 2012.
#include <iostream>
using namespace std;
class dummy {
public:
dummy() {
cout<<"dummy created"<<endl;
[Code]...
So this is the code I have so far, I didn't know it had to be a dynamic array so how would I Utilize dynamic array allocation to size the modal array
#include <iostream>
using namespace std;
int main() {
const int arraySize = 25;
const int patternSize = 10;
[Code] ....