C++ :: Constructor That Initializes A Pointer To Point To The Object
Aug 27, 2013
I have a program that has a base class 'control' and there are 2 dervied classes 'button' and 'textbox'. How do i make a constructor in the 'button' or 'textbox' that initializes a pointer of the data type 'control' to point to the object that invokes the constructor. the code should look like this
class control {
//data
} class button:public control {
buton() {
//code for the constructor
}
}
actually i have an array of pointers of the type 'control' and as soon as any instance of a control like button or textbox is created the constructor should make an element of the array to point to the instance
Write a constructor that initializes a new inventory object with the values passed as arguments, but which also includes a reasonable default value for each parameter.
will copy constructor does object initialization using another already created object? I understand that it can be applied for object initialization and not for assignment.Is it correct?
is it possible to get object name in the constructor? I would like to initialize an object of circle class without any arguments and put some pretty lines in constructor to get and save as table of chars the name of creating object. Is it possible? I work with MSVS2012.
To my best understanding, the compiler will provide me with a deafult constructor only if there are no any user defined constructors, at all. Now consider the following code:
Code: class MyClass { private: int m_data; public: MyClass(int init):m_data(init){cout<<"Ctr called"<<endl;}
[Code] ....
How is it that suddenly, there is a default constructor?
Do I really need to create a separate pointer to point to dynamic arrays?
T* temp = new T[capacity_ * 2]; T* tIter = &temp; //Do these need to be here? T* dIter = &data; //Or can I use *(temp + i) and *(data + i)? (for unsigned int i = 0; i < size_; i++) { *(tIter + i) = *(dIter + i); }
I am creating a Matrix class, and one of the constructors parses a string into a matrix. However, printing the result of the constructor (this->Print()) prints what I expect, and an <object_just_created>.Print() call returns bogus data. How is this even possible?
Snippets below:
Matrix::Matrix(const string &str) { // Parse a new matrix from the given string Matrix r = Matrix::Parse(str); nRows= r.nRows; nCols= r.nCols;
[Code] ....
in the driver program, here are the two successive calls
Matrix mm6("[1 2 3.8 4 5; 6 7 8 9 10; 20.4 68.2 1341.2 -15135 -80.9999]"); mm6.Print(); // mm6.Print() calls bogus data, -2.65698e+303 at each location. The matrix's // underlying array is valid, because printing the addresses yields a block // of memory 8 bits apart for each location
This all compiles ok, but the last line in the code above causes a segmentation fault. I should mention Node is declared on its own in Node.h and what pgm is. including pgm.h in node.
class Base { char * ptr; public: Base(){} Base(char * str)
[code].....
Obj1 is a derived class object where base class char pointer is initialized with "singh" and derived class char pointer is initilized with "sunil". I want to create Obj2 out of Obj1. Separate memory should be created for Obj2 char pointer (base part and derived part as well) and that should be initialized with the strings contained in Obj1.
Here the problem is: Derived class part can be initialized with copy constructor. How to initialize the base class char poniter of Obj2 with the base class part of Obj1. char pointers in both the classes are private.
I tried using initializer list but could not succeed.
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.
#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.
I have pointer object and i have to assign to another variable ( new object ). But if i change any value in new object should not reflect in old object. I did in the below way, it changes the value.
class Test { public: int num; }; Test* obj; obj.num=1; Test obj_n=*obj; obj_n.num=2;
Now both object's num have value as 2; i.e obj.num // has 2 obj_n.num // has 2
Actually my expected result is: obj.num - should have value 1 obj_n.num - should have value 2
My actual scenario is different where Test obj is pointer object, so obj should be pointer object. i have given sample scenario.
The StackElement class contains pointers to some dynamic arrays. When I use the assignment, StackElementArray[0] = iStackElement;, it doesn't copy the complete contents and I have to define an 'assignment operator' function to copy all the contents. I am wondering if there is a way I can assign StackElementArray[0] the pointer to the StackElement object. In that case, I will not need to copy the contents of iStackElement into StackElementArray[0] and will just copy the address.
