C++ :: Pass Object To Class Which Stores It In Container As Unique Pointer
Jul 24, 2013
class A (abstract)
class B : A
class C {
void add ( A(&*?) a )
std::vector<std::unique_ptr<A>> data; //unique_ptr<A> because A is abstract and therefore vector<A> isn't possible
}
upper situation. What is the best way to pass add an object of class B to C?
with C::add(A* a){ vector.push_back( unique_ptr<A>(a) ); }
and
int main() {
C c;
c.add( new B() );
}
This works, but i don't think it's very nice, because you could delete the pointer in main. What happens then with the unique_ptr? I could probably make C::add( std::unique_ptr<A> u_p ); but maybe it can be avoided that the "user" (in main() ) has to create the unique_ptr itself.
i need to pass myboard.board (board is in the class Cboard and it is an array of int) to a function in a class called piece however this is troubling . i need to pass it as pointer os that i could change its value here under is my code.
The following code compiles and runs fine till it reaches line 16 and gets a sigsev violation which I'm not sure about as to why. I have no problem passing the object of type node** into the constructor of base and storing it into the double pointer node** copy;; but when I call the function void pass(node** temp) it crashes.
#include <iostream> class base; class node { private: node** data; public:
I am having trouble working with third party dll's, libs and header files. I am trying to call a function.here is the function that is suppose to be called.
Name IN/OUT Description m_environment IN Optional. Possible values are SANDBOX (default) and LIVE. m_strConsumerKey IN OAuth consumer key provided by E*TRADE m_strConsumerSecret IN OAuth consumer secret provided by E*TRADE m_strToken OUT Returned by the function if successful m_strTokenSecret OUT Returned by the function if successful m_strCallback IN Optional; default value is "oob"
I have to write a program to print pascals triangle and stores it in a pointer to a pointer , which I am not entirely sure how to do. I also have to write the file and read it, then create a binary file. Assignment is attached. I am not the best with programming and especially with pointers. I will post my code below.
Code: #include <stdio.h> #include <stdlib.h> void writePascalTriangle(char *fileName, int heightOfTriangle, int **triangle) { FILE *fp; fp=fopen("writePascalTriangle.txt", "w");
This is confusing to me because it compiles, yet my unique i is passed by R-value reference, without ever being explicitly moved. I thought named objects could NEVER be considered R-value references... Am I wrong to think that the above is extremely dangerous? After the call to "eat", my "i" has been destroyed internally, I could save by passing by value:
But at this point, I'm paying for a (theoretically cheap) move copy, when I could be paying nothing at all... A third solution would be to overload with a const ref version, but at this point, I get an obscure linker error, when I'm really looking for a compiler error...
#include <iostream> #include <vector> #include <string> #include <map> using namespace std; struct bop { string realname; //real name
[Code] ....
Okay, so first thing's first. The program will not compile due to lines 39-45. If I were to change those pointers into regular objects, it will not change the values of my class object. So what is the right way to do this?
I want the user to be able to input the # of employers/programmers into the system. But I cannot do that with an array of classes because when declaring an array; the array size must be constant.
Lets say we have a class that holds a pointer member to another object. If I delete that pointer in the destructor I get an error (and I understand why). My question is : is it possible to overcome that without memory leaks ?
1 #include<iostream> 2 using namespace std; 3 4 class A { 5 public: 6 ~A() { 7 cout<< "~A()" <<endl;
lets say I have a pointer p_unit of type c_unit* (c_unit is an a.b.c.)
I have a function that returns a pointer to a new c_unit object:
c_unit * man_add_unit() { c_unit * local_p_unit; unsigned short int local_run_code; print_man_add_menu(); local_run_code = get_a_run_code(); // this bit just gets user input switch (local_run_code)
[code]....
I assign that to p_unit, then add it to a vector v_units:
p_unit = man_add_unit(); v_units.push_back(p_unit); cout << "New unit added. ";
The whole program runs on a loop, and another thing the user can do is to print out data on c_unit objects pointed to by v_units. The problem is, in that function up there ^ I give the user the option to go back to main menu without creating a unit.
Since "local_p_unit" is declared but not assigned an initial value, I'm guessing the function would return a "null" pointer (which is what's hanging me up). If I just let this run with the above code, and go to print out the unit data, the program crashes.
I tried to make an if thing with p_unit == 0 but this always returns false and doesn't catch the "bad" unit that will subsequently cause a crash.
Btw, I have considered assigning a reference to a generic c_unit object to that there local_p_unit so it won't return null, then remove pointers to that object from v_units at the end of the loop.. But I know there's got to be a better way.
Is there a way to copy a derived class object thru a pointer to base?
For example:
class Base { public: Base( int x ) : x( x ) {} private: int x; }; class Derived1 : public Base { public: Derived( int z, float f ) : Base( z ), f( f ) {} private: float f;}; class Derived2 : public Base { public: Derived( int z, string f ) : Base( z ), f( f ) {}
[Code] ....
The question is whether *B[0] would be a Derived1 object and *B[1] a Derived2 object?If not, how could I copy a derived class thru a pointer to the base class?
I know if i will not use the pointer base class function "virtual double grossPay" will be called for both base class object and derived class object and when i will use pointer with reference to the object because base class function is virtual it will look for same function in derived class and if available it will execute it.
i really don't know why has a error in my code, that pass a pointer of pointer (name of a matrix with 2 dimensions). Here is the source code of a simple example where appears segmentation fault when execute (but compiles normal):
#include <stdio.h> #define LINHAS 3 #define COLUNAS 5 float a[LINHAS][COLUNAS]; void zeros(float **p,float m, float n){ int i,j; for(i=0;i<m;i++)
I have a Point class that's already implemented. My goal is to implement a container class called Line that holds the Point class. I'm not allowed to use any existing container classes for this. Here's what I'm working with:
//File: Point.h #ifndef POINT_H_ #define POINT_H_ class Point { public: Point(int x = 0, int y = 0); Point(const Point & t); virtual ~Point() {};
[Code] ....
How I'm supposed to write Line.cpp...how do I access/add Points to Line without using something like a vector? I probably should've included what I've written so far.
#include "Line.h" /** * Default Line constructor */ Line::Line() {
if i can use a function to use unique for my class and also i want to count how much each of them is duplicated. i mean i have (420,250,420,66,444,777,250) in my list i would like to know that 420 is duplicated 2 times and also 250. Is there a way to get this result ?
list<Patient *> ListePatient ListePatient.unique(g_nas()); // nas is a attribute of the class patient
I am trying to write a poker program. I created a class to create a deck of cards..and then shuffle the deck..Now I am trying to pass value from the deck to an array to deal a hand..so 5 cards to player1[] array.. I tried doing it directly such as.
But I would get error such as [Error] no match for 'operator=' in 'player1[j] = deck[j].Card::toString()'
So then I tried using a pointer..
char *getCard; getCard = new char; for (int j = 0; j < 5; j++) { getCard=deck[j].toString(); }
but I would get this error [Error] void value not ignored as it ought to be. So how can I pass a value from the object deck..to an array? or should I be doing it another way?..I tried to think of a way to do it via a function but really got hung up there..
I need to send same instance of object of a class in two function (Main function and thread function). The class is something like this:
//The class need to have constructor. Class ABC { public: DWORD *IdG; ABC(int number) { IdG = new DWORD[number]; } }obj(32);
The obj(32) is called in following two function. Function F1 is called using thread in main function.
void F1() { obj.test; } int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd) { obj.test1; _beginthread(F1,0,(void*)number); }
The code works well when the object of class ABC is created as shown above. My problem is the value that is passed in the object ('32') is to be read from the file.
If I read the file and create object separately in Main function and function 'F1' then , function 'F1' is not executed.
How to create same instance of object for Main function and function 'F1' with value passed in the object taken from the file.
I got base class called Statistic and inherited classes from it : lsp, cpu, memory. Those methods inheriting some of methods from Statistic and implement also theirself methods. I prepared some new class called ExecuteRequest which is taking Statistic object in the constructor. What i want to achieve is after i put e.g LSP to this class i would like to determinate what specific object it is in this case LSP right? Then having that i would like to put this object to RunRequest method. How can i achieve that? See my code below:
using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace SOAP_testing { public class ExecuteRequest
