C++ :: Move Constructor In Class Definition?

May 5, 2013

I am unable to understand how a move constructor works in this example of code. If someone could break down the process of what is taking place and explain to me on why to use a move constructor.

Code:
class MyString {
MyString(MyString&& MoveSource) {
if( MoveSource.Buffer != NULL ) {
Buffer = MoveSource.Buffer; // take ownership i.e. 'move'
MoveSource.Buffer = NULL; // set the move source to NULL i.e. free it
}
}
};

Example from "SamsTeachYourself: C++ in One Hour a Day"

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C++ :: Simple Class Definition And Constructor

Mar 7, 2015

I keep getting following errors:

multiple definition of `SDL2Graphics::SDL2Start()'
undefined reference to `SDL2Graphics::SDL2Graphics()'

My set up is as follows:

Main.c++:
#include <iostream>
#include "GL/gl.h"
#include "GL/glu.h"
#include "SDL2graphics.c++"
/* Global variables */
int main(int argc, char* argv[]) {

[Code] ....

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C++ :: Difference Between These Two Definition Of Derived Class Constructor?

Jul 27, 2014

I have one base class and one derived class.

class Base
{
protected:
int a, b;

[Code]....

The two definition of the derived class constructor

(Derived(int aa, int bb, int cc) { Base(aa, bb); c = cc; }
and
Derived(int aa, int bb, int cc) : Base(aa, bb), c(cc) {}

looks identical but first one does not work.

So, I wounder what the difference between them?

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C/C++ :: Call To Move Constructor When Vector Pushback Is Called

Dec 29, 2014

#include <vector>
#include <iostream>
#include <iterator>

[Code]....

I am confused for first call to push_back copy constructor is called for second call I am expecting it to move class instance to new memory location there by trigering move and then inserting second class instance expected call:

Copy constructor
Move constructor
Copy constructor
but its calling
Copy constructor
Copy constructor
Move constructor

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C++ :: Derived Class Constructor Using Base Class Constructor?

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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Visual C++ :: Syntax In Class Definition While Inheriting Another Class

Apr 21, 2014

#include "IMyIntData.h"
class MyIntData : public CPMUnknown<IMyIntData>
{

I need to know what this syntax means (including MyIntData in angular brackets after parent class name) where IMyIntData is the Interface from where MyIntData is derived.

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C++ :: Write A Class Definition For A Fraction Class

Nov 25, 2013

Write a class definition for a Fraction class. Its member fields are num and den, both of type int. The constructor builds the default fraction 1/1. It has the following operations:

void plusEquals(Fraction second);
//Adds the second fraction to this fraction like the operator += void minusEquals (Fraction second);
//Subtracts the second fraction from this fraction void timesEquals (Fraction second);
//Divides this fraction by the second fraction void dividesEquals (Fraction second);
// Divides this fraction by the second fraction void reduce();
// Reduces this fraction to lowest terms double todecimal();
//returns the decimal value of this fraction void scan(istream&);
//scans a fraction written with a slash as in ¾ void print(ostream&);
//prints a fraction using a slash Fraction();
//constructs a default fraction with denominator 1, numerator 0 Fraction(int n, int d); //constructs a fraction given value for num and den

2. Write a menu-driven driver program designed to allow thorough testing of your Fraction class.

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C++ :: Multiple Definition Of Class?

Nov 18, 2013

I have a question about multiple definition of class LoaderException.

I have such code:

LevelLoader.hpp
#ifndef LEVELLOADER_HPP
#define LEVELLOADER_HPP

[Code]....

I found way around this, but I would like to know why it shows multiple declarations.

My solution is to declare this class in function body(void LoadLevel()), just before the throw statement. But why can't I define it inside my namespace, but outside function?

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C++ :: Can One Constructor Of A Class Call Another Constructor Of The Same Class

Mar 19, 2015

to initialize this object? Why C++ FAQ says no? Here is my code,

Code:
class A
{
public:
A(int x, char c);
A(int x);

[code] ....

I don't have any trouble to call the constructor A(int x, char c) from another constructor A(int x).

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C++ :: Undefined Reference To Class Definition

Aug 4, 2013

I have successfully built OGDF under directory undefined reference to /home/vijay13/Downloads/OGDF-snapshot/

I have following code in test.cpp under directory /home/vijay13/Downloads/ :

#include <ogdf/basic/Graph.h>
#include <ogdf/fileformats/GraphIO.h>
#include <ogdf/basic/graph_generators.h>
#include <ogdf/layered/DfsAcyclicSubgraph.h>
using namespace ogdf;

[Code] .....

while compiling as following :

vijay13@ubuntu:~/Downloads$ g++ -o test test.cpp -I /home/vijay13/Downloads/OGDF-snapshot/include/

I am getting following error:

vijay13@ubuntu:~/Downloads$ g++ -o test test.cpp -I /home/vijay13/Downloads/OGDF-snapshot/include/
/tmp/ccPE8nCu.o: In function `main':
test.cpp:(.text+0x26): undefined reference to `ogdf::Graph::Graph()' ...................... so on

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C# :: Definition Errors After Changing Name Of Class

Jan 31, 2014

I changed the name of my Invoice class to 'Application' and then it generated errors such as follows

Error9'Invoice.Invoice' does not contain a definition for 'Documents' and no extension method 'Documents' accepting a first argument of type 'Invoice.Invoice' could be found (are you missing a using directive or an assembly reference?)c:userskeildocumentsvisual studio 2013projectsinvoiceinvoicewritefile.cs1840Invoice

Error3'Invoice.Invoice' does not contain a definition for 'Run'C:UsersKeilDocumentsVisual Studio 2013ProjectsInvoiceInvoiceProgram.cs1921Invoice

I have added my classes here, lso I have added the sln to this post.

using System;
using System.Collections.Generic;
using System.ComponentModel;

[Code].....

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C++ :: Class Definition Inside Function Body

Mar 3, 2013

Is this standard-compliant code?

int f() {
class C {
public:
int mf() const {return 1;}
};
C c;
return c.mf();
}

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C++ :: Defining Member Functions Outside Class Definition

Jan 3, 2014

#include "stdafx.h"
#include <iostream>
#include <math.h>
using namespace std;
class Calc {

[Code] ....

when i built it, it showed the following errors:

1>------ Build started: Project: rough, Configuration: Debug Win32 ------
1> rough.cpp
1>e:c programs
ough
ough
ough.cpp(17): error C3872: '0xa0': this character is not allowed in an identifier
1>e:c programs

[Code] ....

Need sorting out the errors!!!

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C++ :: Typedef And Struct Inside Class Definition?

Jul 22, 2013

Can typedef and struct be put inside a class like below?

Code:
class classA {
private:
typedef void(classA::*aFnPtr_t) (); //pointer-to-member function
struct strctA {
int a;
int b[100];
};
typedef struct strctA strctA_t;
typedef void (classA::*bFnPtr_t)(strctA_t*); //pointer-to-member function
...
}

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C# :: Move Class To Its Own Project And Keep Its References?

Apr 3, 2014

I was wondering if there is way to convert a C# class to its own project and it automatically keeps its references.

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C++ :: Can't Initialize Static Data Member In The Class Definition

Apr 17, 2013

"You cannot initialize the static data member in the class definition — that’s simply a blueprint for an object and initializing values for members are not allowed. You don’t want to initialize it in a constructor, because you want to increment it every time the constructor is called so the count of the number of objects created is accumulated."

Why don't you want to initialize it in a constructor?

Edit: Because every time it is called it will set it back to 0 or whatever the initializing value.

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C++ :: Using Template Class - Unable To Match Function Definition To Existing Declaration

May 12, 2013

I am just learning using class template but I keep getting error unable to match function definition to an existing declaration

template <typename T>
class Homework {
private:
string name;
public:
template <typename T>
void SetName(T val);

[Code] ....

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C++ :: Initializing Inner-objects Of Base Class From Driven-class Constructor

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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C++ :: Invoking Base Class Constructor From Derived Class?

May 15, 2013

I understand it is done like this

// Calling the base class constructor
explicit CCandyBox(double lv, double wv, double hv, const char* str="Candy"): CBox(lv, wv, hv)
{
...
}

But how does the compiler know that you are initializing the base "part" of the object?

Or is this the entire reason initialization lists exist, to separate this confusion?

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C++ :: Using Constructor Within Constructor In Same Class

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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C++ :: Creating One Class Object In Constructor Of Another Class

Sep 20, 2013

Suppose I have two classes A and B so how to access object of class A in constructor of B's class as a parameter.

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C++ :: Class With Enum And Constructor

May 29, 2013

I really confused with constructor (default constructor and constructor with parameters)

I coded this problem

and I worked almost, but I stock in constructor

Code:
class Tier {
public:
enum TIER_MAKE

[Code] ....

This is tier class and I have to finish constructor in class car (for simple, I skip detail code) -red things are the parts from class Tier

Code: Car()
: make(NULL), passengers(0), fuelcap(0.0), efficiency(0.0), tier(Tier::nexen)
{ }

[Code] ....

And someone said default constructor part has to be this

Code:
car( Tier::TIER_MAKE p_tiermaker = Tier::nexen )

//after i skip
but default constructor should be no parameter...? isn't it?

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C++ :: Class Course / Constructor Errors

Mar 22, 2014

# include <iostream>
# include <cstring>
#include <iomanip>
#include <cmath>
using namespace std;
class Course
// Creating the class Course

[Code] ....

Errors: Warning1warning C4996: 'strncpy': This function or variable may be unsafe. Consider using strncpy_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS.

[Code] .....

I have to create an Array of type Course and then fill its member dats using various member functions. Those errors are caused by some Constructor defect, which I dont really know what it is.

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C++ ::  Can Use Class Constructor To Run Code In CPP By Itself?

Jan 13, 2015

I recently designed a struct like this

// MyMap.h
typedef std::map<std::string, std::function<void ()>> MyMap;
extern MyMap g_mymap;
// MyMap.cpp
My Map g_mymap;

[Code] ....

It looks useful to implement strategy pattern because it makes a fully separate code block. So I can add a function to the map simply by compiling a source file. It's very simple. I don't need to edit another file.

But when I use it for my existing project, It makes some linking and runtime errors.(vs 2012). I can't recognize exactly why because it is a huge project. Anyway, I have a question that - Is this a safe use of class constructor?

I know that there is no fixed order of running, but in this case I think it doesn't matter. because they are independent. But it is not a common pattern, so I can't decide to use it.

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C/C++ :: Add Copy Constructor To Class?

Nov 15, 2012

This is my class there is a problem with my copy constructor .. is that correct ??

struct Node {
    Type info;
    Node<Type> *next;
};  
template <class Type>
class Queue

[Code] ....

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C++ :: How To Redefine A Constructor From Parent Class

Jul 14, 2014

Firstly I don't really know if this is possible.

This is my Class Diagram: [URL]...

github: [URL]...

I want to redefine the price object of the Book Class. However price is defined at Products Class.

I want the price value change according to the marker value, which is a Book attribute.

If the marker is blue, price gets a value of 10 (e.g.), if it has another value, price is equal to 20.

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