C/C++ :: Initializing Constructor In CPropertyPage?
Aug 21, 2013
Here is a declaration of property class
class CMyPropertyPage11 : public CPropertyPage
Here is the definition
CMyPropertyPage11::CMyPropertyPage11() : CPropertyPage(CMyPropertyPage11::IDD)
I really do not understand the role of the
CPropertyPage(CMyPropertyPage11::IDD)
But I need to derive CMyPropertyPage11 from another CPropertyPage, say CBasePropertyPage adn really need to know how to implement the CPropertyPage(CMyPropertyPage11::IDD) initialization again.
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Mar 6, 2015
I am making a tictactoe program that requires me to have a 3 by 3 two dimensional array of integers, in which the constructor should initialize the empty board to all zeroes. The program complies, but it keeps outputting garbage values and i'm not entirely sure why, My print function isn't complete yet, since I want to print out the array in a tic tac toe format, but i'm more concerned with why it's printing garbage values, here is my code:
Code:
// header file
#include <iostream>
#include <array>
[Code] ....
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Oct 15, 2013
sth is in my mind.
fast way of initializing an object through constructor is
Fred::Fred() : x_(whatever) { }
slow way
Fred::Fred() { x_ = whatever; }
ok. i accept it is faster but why?? what is the difference compiler does.
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Nov 18, 2014
I am trying to create a `std::map` from `std:: string` to a pointer to member function type. I'm initializing the `map` with an initializer list (braced). When I compile, I get a message from the compiler: No matching constructor for initialization.
Example: [URL] .....
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Mar 8, 2015
I am making a tic tac toe program in which they are asking me to have a 3x3 2 dimensional array of integers and have the constructor initialize the empty board to all zeros. They also want me to place a 1 or 2 in each empty board space denoting the place where player 1 or player 2 would move The problem I'm having is, my code initializes the board to all zeros for each element of the array, and prints it out just fine, but I can't figure out how to re-initialize the values in the array to show where each player moves on the board... I was thinking about having a default constructor that has each value set to zero, and then use a setGame function that can change the values on the board to one or two depending on where the player moves....but I don't know if that's possible.....
here is my code
Code:
// header file
#include <iostream>
#include <array>
class tictac {
public:
tictac(int);
[code]....
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Jan 23, 2015
I have a class that defines a window (a popup dialog of sorts), and I want the name of that window to be constant. The only problem is that the name of the popup needs to match the title of the parent window, and I get the name of the parent in the constructor. So how do I go about defining this member variable to be constant and initializing it with a value in the constructor?
I want to do something like this, but I know this isn't allowed:
/* class.h */
class foo {
public:
foo(*parentWindowPtr);
[Code] .....
I should mention that yes the name of the parent window is const char *, and I would like to keep it this way.
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Feb 20, 2012
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.
Is there some proper way to do this?
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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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Mar 1, 2014
i am writing this bank accounts program using structures. i haven't implemented the function before that i want to check if the data is being read and printed. When i build and run the program in visual studio it gives me the following error. "No constructor could take the source type, or constructor overload resolution was ambiguous". Now whats wrong in this program?
/* Bank Accounts Program */
#include <iostream>
#include <string>
#include <fstream>
#include <cstdlib>//needed to use system() function
using namespace std;
const int MAX_NUM = 50;
struct Name{
[code]....
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Jan 25, 2014
VS 2012 / Windows 7 64 bit
class
class myclass {
public:
myclass(){/*stuff here*/}
myclass(int* p) {MyPointer = p; myclass()}
[Code] ....
it works until the myclass(int* p) calls myclass()
then the MyPointer will become CCCCCCCC (NULL value)!
is there a way to stop the second constructor from resetting the pointer value to null?
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Feb 28, 2012
I am trying to use constructor within constructor in the same class. Is that possible. I have tried something and it shows me a error message:
error: type "mainClass" is not a direct base of "glavna"
This is the program I tried:
Code:
class mainClass {
private:
int x,y;
Code] ......
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Jan 1, 2013
Is this example correct? This example from a book
Constructor of the Base Class
Person::Person(char* n="", char* nat="U.S.A", int s=1)
{
name = n;
nationality = nat;
sex = s;
}
Constructor of the Derived Class (inherited from the base class)
Student(char* n, int s=0, char* i=""):
Person(n, s)
Why the initialized list of the base class constructor doesn't match the initialized list of the derived class constructor? I know this book is a little bit old, I'm not sure if this wrong in VC++ 2010?
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Sep 26, 2014
I am working on a homework assignment and have most of the program working, but when I try to compile it keeps telling me to initialize the coin variables in each class. However, they are supposed to be added then removed so I don't want to set them back to zero.
Rewrite the Purse program given in Page 35 with functions to perform insert and remove operations. The function insert (int p, int n, int d, int q) will initialize pennies, nickels, dimes and quarters. The function dollars() will return the dollars. The function remove (int p, int n, int d, int q) will subtract pennies, nickels, dimes and quarters. The function display() returns a new String to print the content of the purse with remaining pennies, nickels, dimes and quarters.
Code:
usingnamespace std;
int insert_money (int *p, int *n, int *d, int *q);
int remove_money (int *p, int *n, int *d, int *q);
int dollars();
int main()
[Code] ....
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Oct 7, 2014
I am having issues with trying to implement JameM's kernel. I page fault attempting to assign the return value of place_ordered_array into the kheap.The malloc function should remain between 10000000-20000000 yet I exceed this. I have a hunch it's due that I am using grub2 (he uses legacy) and it loads modules at a higher address. I tested this by debugging at alloc and found that the function cannot handle above about 20000000. Am I on track to say I must attempt to move the module or code to prevent trampling or that I should switch to legacy.
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Jul 24, 2014
Here I'm trying to initialize PersonFactory::ethnicSurnames just once for the entire run of the program:
#include <iostream>
#include <string>
#include <vector>
#include <array>
enum Country {India, China, France, NumCountries}; // plus many other countries
struct School {}; struct Mall {}; struct HockeyArena {};
[Code] ....
Output:
PersonFactory::initializeEthnicNames() called
Carrying out the initialization...
PersonFactory::initializeEthnicNames() called
PersonFactory::initializeEthnicNames() called
PersonFactory::initializeEthnicNames() called
PersonFactory::initializeEthnicNames() called
numberOfTimesInitialized = 1
As you can see, even though five PersonFactory objects were constructed, the ethnicNames initialization only occurred once, as desired. However, there are some issues with my method. First of all, the use of the comma operator is ugly in my opinion. But fashion statements aside, PersonFactory::initializeEthnicNames() is still called multiple times, which is not good, even though it correctly avoids reinitializing ethnicNames after the first call. Also, I now forever get the annoying compiler warnings that the bool namesInitialized is never used, which is true, thus wasting a small bit of memory. And finally, I cannot declare ethnicNames const now, and it is supposed to be const. Any better way to accomplish what I'm trying to do?
By the way, the reason why I don't initialize ethnic names outside the class as is normally done for static data members (and that would indeed allow me to declare it const) is because it would get messed up if I later change the order of the elements in enum Country. Hence actual lines of initializations I think are needed. And I do want ethnicSurnames inside PersonFactory, because I feel it really does belong there. Also, PersonFactory is not to be Singleton, because it has data members that depend on some parameters in its constructor (e.g. geographic location).
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Oct 24, 2013
I want to know how to make variables during the program. for example in a program i want to have the player be able to create their own spells or add their own weapons to the game without having to edit the source code. i use sfml 2.0
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Feb 4, 2014
I came across a piece of c++ code that seems to be initializing a class object like this:
ImapMailbox *mailbox;
Now the class looks like this:
class ImapMailbox {
public:
ImapMailbox();
ImapMailbox (const QString& mailbox);
~ImapMailbox();
// Methods
void addMessage (ImapMessage *message);
[Code]...
And the constructor looks like this:
ImapMailbox::ImapMailbox()
: d(new ImapMailboxPrivate)
{
d->unseen = d->exists = d->recent = 0;
d->readWrite = false;
d->flags = 0;
}
But this does not seem to be an array like object. So what exactly could this be pointing to?
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Mar 31, 2014
I'm working on this program, and when i run it for 'p', 'P', or for a incorrect service code a error message pops up saying that "totalCost is being used without being initialized". I don't want to change it to switches, case, and breaks now because I've come too far to change it all. I have that variable right here just below.
#include <iomanip>
#include <iostream>
using namespace std;
int main() {
int acctCode;
double nightCost;
double totalCost;
[Code] ....
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Dec 20, 2013
Code:
struct foo {
char label[64];
int state;
} bar[3] = { };
Will the above code ALWAYS initialize to 0 all objects:
bar[0].label
bar[0].state
bar[1].label
bar[1].state
bar[2].label
bar[2].state
Using gcc and g++, it does in my testing But was wondering if it can be unsafe under some circumstances.
I even tried without = { } and it is still initialized to 0 for all objects!
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May 17, 2014
So I'm writing a small program for class, and for some reason I keep getting an error when trying to initialize head to NULL. Even threw in the namespace just to see, nothin'.
#ifndef NUMBERLIST_H
#define NUMBERLIST_H
using namespace std;
[Code].....
There's my header file. Not sure what I'm doing wrong with the constructor.
EDIT: Got it to work with nullptr, but still curious why that isn't working
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Feb 25, 2014
How to initialize this array of structures in my code
struct CustomerAddress; {
string street;
string city;
string state;
int zip;
[Code] ....
I am going to be using a boolean variable to mark whether or not a specific field has had data entered into it. I figure the best way to do that is to initialize all the elements of the structures to 0. However, with strings and with the nested structure, I'm not sure how to do this.
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Apr 14, 2014
I'm wondering what is the "best" way to initialize a bitfield struct. I have this bitfield, defined as:
Code:
struct S
{
unsigned int a : 1;
unsigned int b : 1;
};
If I'm "using" the bitfield, I can initialize it easily when declaring it, as so:
Code:
int main()
{
S s = {0};
}
Now, the issue I'm facing is that I want to embed S inside another struct, which I'll name "outer". EG:
Code:
struct Outer
{
S s;
};
I'm wondering what the "best" way to have Outer initialize S is? I've seen a lot of people use the "union" approach:
Code:
struct Outer
{
Outer()
{
u.all = 0;
}
union
{
unsigned char all;
S s;
} u;
};
but:This adds an extra field depth (the union's u)Does bit hacking, in a way (is the bitfield as large as my field?) I'd have wanted to initialize the field in my constructor, as so:
Code:
Outer::Outer() : s({0})
However, this would appear to be a C++11 feature only.
I have, however, "observed" that by simply "empty constructing" s, eg:
Code:
Outer::Outer() : s(){} //Initialize s ?
vs
Outer::Outer(){}
Then my bitfield "appears" initialized.
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Mar 14, 2013
This program is compiling just fine but is not running. Even, Main is not initializing, Here is my code
Code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int pow2(int n) {
printf("POW2");
int pow = 1;
[Code] ....
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Aug 1, 2013
How to initialize double pointer array..?
int (**aLines)[2];
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Oct 30, 2014
Im familiar with fstream and know how to read in data, given that there is one type per line.
But I have a file that has multiple lines each containing a string (an address) and two double values (latitude and longitude).
Looking for support with the logic part of reading in data and initializing them to member variable.
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Dec 29, 2013
is it possible to create a dynamic array with all entries in it equal to 0?
int** adjMatrix;
adjMatrix= new int*[numOfVertices];
for(int i=0; i<numOfVertices; i++){
adjMatrix[i]=new int[numOfVertices];
}
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