I just read and have known for a while that classes are private (members and inheritance) by default and structs are public. But my question then comes what if.. a struct inheriting from a class or a class inheriting from a struct?
View 3 Replies#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.
If Yes, then why this syntax does not works :
class Derived : public Base {
public:
Derived& operator=(const Derived &rhs) {
operator =(static_cast<const Base&>(rhs));
[Code] ....
I'm making a minimal spanning tree class that inherits a graph class, both are templated. This is my mstree.h so far:
#ifndef _MSTREE_H_
#define _MSTREE_H_
#include "graph.h"
namespace MSTreeNameSpace
[Code]...
and I keep getting these errors:
mst.h:9:25: error: expected template-name before ‘<’ token
class MST : public Graph<T>
^
mst.h:9:25: error: expected ‘{’ before ‘<’ token
mst.h:9:25: error: expected unqualified-id before ‘<’ token
I've been working on a path-tracer for some time, and all along I've used structs instead of classes for vectors and matrices. Today I changed all of them to classes instead, changing none of the actual function bodies themselves, and the results were miserable to say the least.
Here's a render form before the change: [URL] ....
And here's the same render after: [URL] ....
Why this is happening, considering that none of the actual function-bodies have been changed, except for what little is needed to make the change from class to struct.
while writing code i got a question. For example i created a class named as unit.
Think a simple game, and the unit class will belong the units.İf i give the preferences as private one by one, it will be irregular. For a detailed game; height, weight, race, hair preferences, eyes... Strength, dexterity, charisma, intelligence, wisdom, constution... experience, damage, armor...
and should i use struct to group them? And how to can i use struct at the inside of class as private?
I'm trying to learn as much C++ as I can. I was writing a program that mixes linked lists and classes. There is the class "Obj" which only holds an integer called 'data' and the classic "struct node" structure for linked list, but this time the "node" structure will hold an instance of "Obj" Class and the next* pointer.
#include <iostream>
using namespace std;
class Obj {
private:
int data;
public:
[code]....
I am making a snake game just to give some context.
//LevelObject.hpp
class LevelObject {
public:
virtual void Update() = 0;
virtual void Draw(Canvas& canvas) = 0;
protected:
Vector3 location_;
[Code] ....
The problem I have is with the Size constructor and the abstract class LevelObject which size is a member of.
The compiler error I get is:
C:Program Files (x86)ProgrammingProjectsUniversityprg_interactivesnakey_takeysrc..inc..incPlayer.hpp|17|warning: non-static data member initializers only available with -std=c++11 or -std=gnu++11 [enabled by default]|
C:Program Files (x86)ProgrammingProjectsUniversityprg_interactivesnakey_takeysrc..inc..inc..incPlayer.hpp|17|warning: non-static data member initializers only available with -std=c++11 or -std=gnu++11 [enabled by default]|
[Code] .....
However I do invoke the copy constructor when I pass a variable of type size to the constructor in this line:
size_ = Size(s);
But the problem is that its complaining that the abstract class LevelObject doesn't invoke the constructor, which it shouldn't.
Is it any different when using a class in my code. My previous code i define my struct like this
Code: #include <iostream>
#include <fstream>
#include <string>
struct{
[Code] .....
or do i still define it the same way at the top of my code.
How to get relative memory address of members of Class or Structure ? I want to auto scan the members of Class/Struct, and show the address/value like the "watch window" in debug mode of popular C/C++ IDE software.
View 2 Replies View RelatedI would like to have a unmodifiable standard of WAVEFORMATEX defined as a member of a class of mine. Something like:
class InputTest {
public:
const WAVEFORMATEX StandardWaveFormat;
public:
void TakeInput(WAVEFORMATEX pFormat);
};
Then in my cpp file to hard-code the values:
WAVEFORMATEX InputTest::StandardWaveFormat {
//Instantiate WaveFormat -- PCM standards
StandardWaveFormat.wFormatTag = WAVE_FORMAT_PCM;
StandardWaveFormat.cbSize = 0; //extra information sent over stream. Usually ignored in PCM format.
[Code] ....
I get the following errors starting with the header file:
Error1error C2146: syntax error : missing ';' before identifier 'StandardWaveFormat'
Error2error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
both associated with the "const WAVEFORMATEX StandardWaveFormat; " line.
Here's a link to the WAVEFORMATEX struct: [URL] .....
Then the cpp source code is probably way off. Let me know if you'd like to see the errors associated with that.
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
...
}
I am not exactly sure how to do this and i keep running into problems. This is my code here that works.
Code:
#include<iostream>
using namespace std;
struct record {
double quiz1;
double quiz2;
double midyear, midyear_one;
[Code] .....
i've defined an strcuct in .h file and i read its variable in a method in .cpp file ,but i'v got error.
.H file:
class myclass{
public:
struct opt_struct
[Code]....
when i declare the struct without static , it doesn't recognize my struct and with static i face linker error:
Error33error LNK1120: 1 unresolved externals
I am trying to create a class type structure using struct instead of classes.
Code:
#include <iostream>
#include <stdlib.h>
using namespace std;
struct myclass {
int * array;
int nelements;
[Code] ....
Guess what I am asking is using the pointer in the first code section better or is there another way'. I don't know about making the second code work.
at my work we use a static analysis tool and it is pointing out some uninitialized variables. One of which is a class member variable which is a C struct. Now, that variable is already declared in the header file for the class.
Currently in the class constructor I am doing:
Code:
memset( &thestruct, 0, sizeof( thestruct ) );
Is there a C++ way to do this? I Googled this but all I really found was:
Code:
StructDef thestruct = {};
Which doesn't really apply here.
I have a variadic base class with a pure-virtual function per type:
Code:
template <typename ... Types>
class Base;
template <typename T, typename ... Types>
class Base<T,Types...>: public Base<Types...>
{
public:
using Base<Types...>::doSomething;
[Code] ......
Now, I'd like to inherit from it using another variadic class, which provides implementations of doSomething(), but I run into trouble --- where do I indicate it derives from Base?
Code:
template <typename ... Types>
class Derived;
template <typename T, typename ... Types>
class Derived<T,Types...>: public Derived<Types...>
[code]....
I see two possible approaches:
First, virtual inheritance *might* get me what I want, but I don't know how bad a performance hit that might be.
Second, I could do some magic where the full set of types is captured in a tuple at the lowest level and continually passed up, then re-expanded in the base case to indicate Base inheritance. However, I'm not sure if that can be done in an unambigious manner; I can't have two variadic packs at once (Types... and the tuple contents), and I'm not sure if there's a way to use enable_if to check if an arbitrary template type is any kind of tuple.
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?
I am trying to inherit from class but the same error is appearing
Code:
1>c:userskthdu_000documentsvisual studio 2010projects
ectangle
ectangle1crectangle.h(1): error C2011: 'Crectangle' : 'class' type redefinition the following is my classes
crectangle.h
Code:
class Crectangle{
[Code] ....
Code:
class CUser {
public:
CUser();
~CUser();
protected:
std::string firt_name;
std::string last_name;
[Code] .....
How would I go about shrink the duplicate data set from CWorksheetTwo? For CWorksheetTwo has both CUser and CUserEx, and I only need CUserEx, and all other classes are happy with CUser
Since there is no such thing virtual variable what are my choices? In CWorksheetTwo set users to NULL and use another exclusively? Change CSettings variable to template <class T> std::vector<T>users?
#include <stdio.h>
#define MAX_USERS 20
struct {
char ID[10];
char Name[40];
int Pos;
[Code] .....
I was attempting something weired with address to move data around when I discovered that the size of the array is not what I expected. I am passing this structure as &Users to a function that declares it as a void *, then I can deal with chunks of data (memmove) and not have to worry about index or things like that. However...sizeof is returning something I do not understand.
Im having trouble creating a struct within a struct node. the program suppose to hold students firstname, lastname, and gpa in a node therefore creating my linked list. Line 26 keeps saying that cannot convert parameter 2 from 'studentType to std::string
#include <iostream>
#include <string>
using namespace std;
struct studentType{
string firstname;
string lastname;
double gpa;
[code].....
"
#include <stdio.h>
struct datastructure {
char character;
};
void function(struct datastructure** ptr);
[Code] ....
These codes give these errors:
error: request for member 'character' in '* ptr', which is of non-class type 'datastructure*'
error: request for member 'character' in '* ptr', which is of non-class type 'datastructure*'
These errors are related to
"
*ptr->character='a';
printf("Ptr: %c",*ptr->character);
"
I want to access "character" data inside the structure "trial" by a pointer to pointer "ptr" inside function "function",but I couldn't find a way to do this.
So why does this not work? As an example:
struct example {
int x; int y;
};
int main() {
example variable;
variable.x = 1;
variable.y = 2;
map<example, int> something;
something[variable] = 3;
return 0;
}
And I get a very long error message from the compiler. I tried using an enum as the key as well and that worked just fine, but I guess that's just the same as having an integer as the key. But anyway, what's the problem with this? Is there any way to make it work?
There are two ways to access the members of class A inside class B:
1) Making an instance of class A in class B
2) Deriving class B from class A
So what is the basic difference in both ways as we can do same kind of work with both ways?
how can I call and print the Pointer:
ptr->address
Code: #include<stdio.h>
struct account {
int address;
int value;
[code]....