Basically, I need to set a variable outside of the constructor and make it accessible to the entire class.
It would need to work something like this:
#include <iostream>
#include <string>
template <typename MT> class CallbackFunction
{
[Code].....
This keeps giving me the error
ecg.h:18:11: error: field "next" has incomplete type
How do I do what I need? It does the same thing whether I use a class or a struct. This is C++ code
struct ECG_node {
double voltage;
clock_t time;
ECG_node next;
[Code] .....
class Date
Date(int=1, int=1, int=1990);
class Person
Person(string="", string="", Date=NULL);
class RealEstateAgent:Public Person
RealEstateAgent(string="",string="",Date=NULL,Date=NULL,int=NULL, double=0.0);
}
[code]....
how can I assign default values with Customer object and RealEstateAgent?
What is the purpose to declare constructor as protected?
View 13 Replies View RelatedTheres a class named "A" which has got a static function named "sfA".Now I instance an object of class A and call a method from A called "fA".
The method fA calls sfA. And now the issue is: i need the value of a member from the object which called fA respectivly sfA, inside sfA.Is there a smarter way to get the value of the member as to declare an new parameter for the sfA? sfA has to be static.
i am trying to describe the unusual situation where you declare a class member function with this format:
bool class::function_name(void) const
Specifically where the 'const' follows the parameter list. It is my understanding this is a very useful way of ensuring that whatever code you put in the function definition cannot change any data members of its class.
However I have recently read that this form of declaration should not be used as it leads to less optimized and slower code. Is this correct?
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?
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).
I have little problem which causing memory leaks.
Parent > Multiple Child(Parent parent) > Child destructor deleting parent => next Child destructor crash
Example code: without using:
class Parent {
public:
Parent() {
for(int i = 0; i < x; ++i) {
for(int j = 0; j < y; ++j)
childs[i][j] = new Child(this);
[Code] ....
If you read code, on Parent destructor i = 0 & j = 1 its going crash.
Parent will be deleted aswell, but it give me assert: _block_type_is_valid(phead- nblockuse)
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.
is it possible to don't declare an object for a class and use the function of this class ? i saw a code use this but i cannot find it again .
View 7 Replies View RelatedHow can I forward declare an inner class?
I currently have this:
Code:
class Enigma
{
public:
Enigma()=delete;
Enigma(char r1,char r2,char r3,char r4, char r5, char r6, char r7, char r8, char r9, char r10);
~Enigma(){delete[] R;}
Enigma(const Enigma& rhs)=delete;
Enigma& operator=(const Enigma& rhs)=delete;
[Code]...
I'd like to be able to define Rotor outside of Enigma, but the compiler complains about incomplete types.
i hit the point where i have two class templates that are dependent on each other (in detail, class a stores a pointer of class b), creating a cyclic include issue.
Usually i resolve this with a forward declaration, but i cant seem to figure out how to do it with a template class.In fact, ( i think) i got it to work for this :
Code:
template<typename T>
class a
{
public:
T x;
}
but not for this:
Code:
template<int b>
class b
{
public:
int getb(){return b;}
}
Where the template is not for a specific "type".
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 .
I wanted to add that the template argument is needed because its a "special case" but if that doesn't work what would be the next best way to solve this problem. I want to be able to declare the const size of the array outside the class far removed from it actually. I'm actually going off this page
[URL] .....
Heres the code
#include <iostream>
template <int F>
class C
{
[Code]....
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?
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] ......
I've been wondering about something for a while:
Is it possible to declare a struct/class, in a cpp file, designed for local use, but with internal linkage?
The usecase is that every once in a while, I want to wrap "startXXX+endXXX" function pairs in a simple RAII struct. I just declare the struct in my cpp and use it once.
However, if I do this, (AFAIK), the compiler will generate an entry in the link table, which means I could potentially have link conflicts if I declare the same struct twice in two different cpp files.
Unless I'm mistaken, since the struct is declared in the same cpp that it is used, I wouldn't need external linkage. Is there a way to avoid it?
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.
View 6 Replies View RelatedHow to initialize a static member of a class with template, which type is related to a nested class?
This code works (without nested class):
#include<iostream>
using namespace std;
struct B{
B(){cout<<"here"<<endl;}
};
template<typename Z>
[Code] ,....
I am writing a program which is using SDL library. I have two different classes which one of them is Timer Class and the other is EventHandling Class.
I need to use some member functions and variables of Timer in some Eventhandling Class member functions, Although I want to define an object of Timer in int main {} and relate it to its member function that has been used in Eventhandling member function in order that it becomes easier to handle it, I mean that I want to have for example two objects of timer and two objects of Eventhandling class for two different users.
I do not know how to relate an object of a class from int main{} to its member function which is being used in another class member function.
Lets have it as a sample code:
class Timer {
private:
int x;
public:
Timer();
get_X();
start_X();
[Code] ....
So I have an ImageManager class, Board class, and Box class. In Board.h I can declare ImageManager imgr; and in Board's constructor I can use imgr and its functions and such. However, in Box.h when I try and declare ImageManager imgr; I get the error "cannot access member declared in class ImageManager". Both declarations are under private, and exactly the same, but one doesn't work. Also, is there a way to only have one instance of ImageManager?
View 19 Replies View RelatedI 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?
# 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.
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.
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] ....