C++ :: Template Operation - Cannot Access Non-Public Members
Feb 5, 2015
Code:
template <size_t s>
class foo {
public:
foo()
{
}
template <size_t l, size_t r>
[Code] .....
The above doesn't want to compile.
error C2995: 'foo<l+r> operator *(const foo<s> &,const foo<r> &)' : function template has already been defined
see declaration of 'operator *'
see reference to class template instantiation 'foo<s>' being compiled
with
[
s=4
]
If I change the operator to return a foo<s> it does compile (but that's not the behaviour I need).
if I move the operator to outside the class (removing the 'friend') it does compile and behaves how I need, but I can't access non-public members so I can't write the implementation correctly.
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Feb 9, 2015
I have a class like this
PHP Code:
template<class X>
class A {
X m_x;
public:
X* foo();
X* bar();
//others are not related to X
};
I would like to get rid of
PHP Code: template<class X>
For class level but still use it for members. Like this
PHP Code:
class A {
X m_x;
public:
template<class X>
X* foo();
template<class X>
X* bar();
//others are not related to X
};
However, I am still stuck at
PHP Code: X m_x;
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Sep 8, 2014
How to access the name and file name members on line 42 and 43?
Code:
typedef struct {
char * name;
char * filename;
} FILES;
FILES * files[256];
}
[code]...
How to access the name and filename from within function?
*files[count].name = chTmp;
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Sep 11, 2014
files.c
Code:
#include "include/types.h"
#include "include/gaussian.h"
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
[Code]....
I need to access the members .name and .filename to allocate memory and copy strings in there.
Code:
files[count]->name=malloc(64);
files[count]->filename=malloc(64); SIGSEGV error
How to make the reference working?
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Jul 12, 2013
It's hard to give a precise title but here is the question in detail: I have a class, something like this:
Code:
class classA{
public:
void fnA();
...
};
and another class that contains objects of classA:
Code:
class classB{
public:
classA A1;
classA A2;
classA A3;
vector<classA*> vA;
...
};
classB B1;
Now is it possible to access B1.vA from B1.A1.fnA() through some kind of pointer chain like this->parent->vA ? If so
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Nov 12, 2013
How does an object access its private data members in copy constructor.
The relevant part of the code: Code: C::C(const C &obj)
{
x = obj.x;
y = obj.y;
}
Normally the object1 called "obj" cannot access its private data members outside. But in this situation it can access. How can it be explained?
Here are the complete code:
Code:
#include <iostream>
using namespace std;
class C{
public:
C(int,int);
C(const C &);
[Code] .....
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Oct 22, 2014
I am doing C++ data structures exercises, and I am still learning some of the more basic concepts. I have a parent class:
template<class T>
class linkedListType {
public:
protected:
int count;
nodeType<T> *first;
nodeType<T> *last;
private:
};
Derived class:
#include "linkedListType.h"
template<class T>
class orderedLinkedList: public linkedListType<T> {
public:
void mergeList(orderedLinkedList<T> &list1, orderedLinkedList<t> &list2) {
first = list1.first;
...
} private:
};
There is more code in my mergeList() function, but I included the line that is giving me problems. The error that my CodeBlocks compiler is giving me is that 'first' was not declared in this scope.
Strangely enough, if I change it to this->first, the error disappears.
1. Why does it not recognise 'first'?
2. Why would this->first work at all? Is the 'this' object a smart pointer?
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Jan 17, 2013
I have a little problem with template classes and their specialization. Here is a short example:
template <typename T>
struct A{
// some typedefs
[Code]....
The above example is not compiling, because of the assignment of the const static double. Double needs a constructor, but that doesn't work (or seems not to work) with static.
I'm not sure, if it works at all in C++ that way. All I want is a template struct with some typedefs and a constant which is different for different specializations. Don't think it has to be static, but that would be better style, wouldn't it?
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Apr 17, 2013
From my book:
"A static function might have this prototype:
static void Afunction(int n);
A static function can be called in relation to a particular object by a statement such as the following:
aBox.Afunction(10);
The function has no access to the non-static members of aBox. The same function could also be called without reference to an object. In this case, the statement would be:
CBox::Afunction(10);
where CBox is the class name. Using the class name and the scope resolution operator tells the compiler to which class Afunction() belongs."
Why exactly cant Afunction access non-static members?
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Jul 7, 2012
I've been writing my own implementation of quicksort in a .h file. I've gotten to the point where I think I'm done with the algorithm, so now I'm trying to make it so that if someone includes "quicksort.h", they will only have access to certain functions in the file. Kind of like public and private functions in a class, but without the "class" part of it. How do you do that?
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Mar 6, 2015
How to properly pass both private and public variables/functions from one class to another?
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Feb 23, 2013
I have read the book over and over and I thought I understand "CLASS". But when I applied it and write the code the compiler tells me that there is a compiling error.
1. I have this method addProduct(Product* pProduct) in a Class called ProductRack, the code is in ProductRack.cpp file. The declaration of the Class methods and private variables are in ProductRack.h header file.
2. But when I call a method in the DeliveryCHute Class from the ProductRack Class I get a compiler errors which are these:
A.IntelliSense: a nonstatic member reference must be relative to a specific object
B.error C2352: 'Project1::DeliveryChute::insertProduct' : illegal call of non-static member function
And this is causing the error:
if (Project1::DeliveryChute::insertProduct(pProduct) == false)
//THIS IS JUST ONE METHOD INSIDE ProductRack.cpp
bool
Project1::ProductRack::addProduct(Product* pProduct) {
// Todo : Implementing
if (Project1::DeliveryChute::insertProduct(pProduct) == false)
return true;
[Code] .....
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Jul 27, 2014
I need to run a public domain code in Molecular Dynamics. I have a Knoppix 7.2 system with Geany and gcc 4.7.2-5 and g++ 4:4.7.2-1 .
I need to compile this code and create a binary but can't.
The output:
gcc -o md md.c
/tmp/ccODg4eA.o: In function `compute':
md.c:(.text+0x718): undefined reference to `sin'
md.c:(.text+0x72a): undefined reference to `pow'
md.c:(.text+0x794): undefined reference to `sin'
/tmp/ccODg4eA.o: In function `dist':
md.c:(.text+0x8f9): undefined reference to `sqrt'
collect2: error: ld returned 1 exit status
note that since this is a Public Domain code, I have not altered it. The main code:
#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <math.h>
#include <string.h>
int main ( int argc, char *argv[] );
void compute ( int np, int nd, double pos[], double vel[],
double mass, double f[], double *pot, double *kin );
[code]....
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May 18, 2014
I've finally managed to do something with the combo box but knock down one wall it's like there's another one five inches behind it. What I mean is I've figured out how to add items to the combo box and have them show images in my picture box. Only problem is when I went to debug my combo box kept looping it's options over and over and over.
Private Sub
xpmaleskincolorselect.Items.Add("Tone1"); malesprite.Image = My.Resources.Resources.XP_Female_clear;
xpmaleskincolorselect.Items.Add("Tone2"); malesprite.Image = My.Resources.Resources.XP_Male_tan;
xpmaleskincolorselect.Items.Add("Tone3"); malesprite.Image = My.Resources.Resources.XP_Male_dark;
End Sub
The subs, I know they aren't right but its just to show I know where they go. Anyway using Private Sub and End sub doesn't seem to work. I'll type them in then at the error box at the bottom it'll say that it doesn't exist in the namespace. Same thing happened when I tried to add public class beforehand to see if that would work same thing about the name space.
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Apr 5, 2014
I'm trying to create a public and static field in a class called ResourceManager. But when trying to access the field even from inside the class it wont work. I'm getting this error message:
Error 1 error LNK2001: unresolved external symbol "public: static int ResourceManager::num" (?num@ResourceManager@@2HA)
Here's my code:
ResourceManager.h
Code:
class ResourceManager {
public:
static int num;
static void loadContent();
[Code] .....
I'm using Visual Studio 2012.
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Sep 9, 2013
if we don't provide the acces modifiers for base class and we need to manipulate the private data of base class in derived class. Is there anyway to acces the private data members? Here's a coding example
class A {
private :
int a;
};
class B : public class A {
public :
void displayA() { cout<<a<<endl; }
};
how i can acces the a of base class A in derived class B without acces modifiers.
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Dec 5, 2013
I'm trying to implement a simple template array class, but when i came into the operator< i actually have to use a template :
my code is something like :
template<typename _Type, std::size_t _Size>
class array {
public :
[Code] ......
but i am having an error of shadows template param 'class _Type' is it w/ the name conflict between the array template parameter and the function template parameter ?
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Nov 6, 2013
Error1error C2955: 'DoubleLinkedListInterface' : use of class template requires template argument listdoublelinkedlist.h10
Error2error C2244: 'DoubleLinkedList<T>::DoubleLinkedList' : unable to match function definition to an existing declaration doublelinkedlist.cpp7
Error3 .cpperror C2244: 'DoubleLinkedList<T>::~DoubleLinkedList' : unable to match function definition to an existing declaration 12
.h
#pragma once
#include "DoubleLinkedListInterface.h"
#include "Node.h"
#include <iostream>
[Code]....
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Mar 13, 2015
I am just trying to get a code going for a mock test and to get use to the getline and IF operations, but it seems I have ran into an issue[URL] is a link to the code I have written, and I can use getline to give a value to my variable, but it seems like it gets lost once I try to use the IF function. Am I not using the right variable type?
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Dec 7, 2014
Why doesn't this compile?
struct hi(){
void other();
}histructure;
void hi::other(){
std::cout << "Hi!" << std::endl;
[Code] ....
Makes no sense the structure is written before the structure member function is called so why is there compile errors ??...
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Apr 12, 2015
So I have this class
class DataBase
{
// Change the connection path here to your own version of the database
public SqlConnection con = new SqlConnection(@"Data Source=(LocalDB)v11.0;AttachDbFilename=|DataDirectory|UberDatabase.mdf;Integrated Security=True;");
public DataBase()
{
}
}
And in the same namespace as this class I have a form that calls it like so:
DataBase dBase = new DataBase();
SqlCommand trythis = new SqlCommand("Register", dBase.con);
However, I'm getting the field initializer error on dBase.con. I'm not sure why, but when I call the database from another file (program.cs) it works fine this way.
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May 27, 2013
I have a generic template class with another template in one of its types. Now I want to specialize one of its methods for a particular (template) class, which leads to a compile error, however.
Here is the example:
#include <stdio.h>
template<typename Type>
class Obj1 {
public:
void ID() { printf("Object 1, size = %zu
[Code] .....
GCC ends with:
:35:27: error: type/value mismatch at argument 2 in template parameter list for ‘template<class Type, template<class> class O> class Foo’
:35:27: error: expected a class template, got ‘Obj2<Type>’
What is wrong with the specialization? Can it even be achieved and how (if so)?
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Nov 2, 2014
how I want the code to look. Only problem is it doesn't work (Line 11). I have some experience with templates but I'm not a pro.
Basically I want the "Channels<3>" to be a type that I can use to specify a Cable with similar to vector<float/int> it would be Cable<Channels<2 or 3>>.
What have I messed up with the syntax?
#include <iostream>
#include <vector>
using namespace std;
[Code].....
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Mar 14, 2014
I have a function:
template<class Iterator, class T>
void a(Iterator, Iterator, const T&);
and I want to be able to simplify calls to 'a' with calls like
a(someIteratableContainer);
instead of having to call:
a(someIteratableContainer.begin(), someIteratableContainer.end(), valueOfTheContainersElementType);
I also want to be able to generalize the function to handle any of the standard iteratable contains: array, vector, deque, whatever.
I was under the impression I could write:
template<template<class T> class U> a(U<T>& container) {
a(container.begin(), container.end(), g(T()));
}
where 'g()' returns an object of the element type. However, the compiler is claiming, no matter how I write a call to the overload, the original template is selected and/or the overload is invalid, depending on the various ways I attempt to write said overload.
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Jan 27, 2013
Code:
int i=5,j;
j=++i + ++i + ++i;
printf("%d",j); //22
i=5;
j=i++ + i++ + i++;
printf("%d",j); //19 Shall not it give 21 and 18 respectively?????
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Jun 2, 2013
I need to run some operation if a key from keyboard is pressed. so I go with
Code: c=getchar();
to get it read. yet the user could press a key anytime; so I'd need some if-loop. no plans on how it'd look like though...I suppose something like this below wouldn't work right?
Code:
if(getchar()==1){
..
}
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