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.
well i create a State.h class
#ifndef STATE.H
#define STATE_H
class State {
public:
virtual void handle_action() = 0;
virtual void update() = 0;
virtual void render() = 0;
};
#endif //STATE.H
What i'm trying to create is a simple State Manager for SFML! I created another class that inherits State.
#pragma once
#include "state.h"
class FirstState : public State {
public:
FirstState();
~FirstState();
void handle_action();
void update();
void render();
};
So the question is this, each state that i have will inherit the State class. However, i wanted to perhaps add each state object into a vector array. But i'm not sure as to what data type it be? I have a state manager class that will contain the vector.
What i want to do is this, each game state will create an object that will inherit functions from the state.h class. I want to store them all in a vector array, but each object is clearly named different. My curiosity was wondering, since all those different states inherit the State.h class, can i simply create a State Object std::vector<State> *states; that will contain all those different state objects?
[URL]....
how to create a base class that is derived (inherited) by three other classes?
View 12 Replies View Related"A nested class has free access to all the static members of the enclosing class. All the instance members can be accessed through an object of the enclosing class type, or a pointer or reference to an object."
How can the members be accessed through an object of the enclosing class type? I understand the pointer and reference part because for them you dont need the full definition, but for creating a object you do?
Also it has free access to all static members because the nested class is part of the enclosed class and with static it exists in everything inside the enclosing class? Right or am I missing something?
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]....
how to use a Class structure to create a program that reads in two rational numbers and adds them, subtracts, multiplies, and divides them.
View 3 Replies View RelatedClasses defined with struct and union
Classes can be defined not only with keyword class, but also with keywords struct and union.
The concepts of class and data structure are so similar that both keywords (struct and class) can be used in C++ to declare classes (i.e. structs can also have function members in C++, not only data members). The only difference between both is that members of classes declared with the keyword struct have public access by default, while members of classes declared with the keyword class have private access. For all other purposes both keywords are equivalent.
The concept of unions is different from that of classes declared with struct and class, since unions only store one data member at a time, but nevertheless they are also classes and can thus also hold function members. The default access in union classes is public.
The above is a statement taken from a C++ tutorial. So I understand classes a bit better now but the above quote doesnt make too much sense. Is it saying that you can have a class within a class?
how I can create a structure that pointing to another different structure. And also passing structure to function.
View 3 Replies View Related"
#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.
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 View RelatedI have the code bellow, and i print the data but cannot assign it to global variable.
struct frequency_data {
char frequency[10];
int32 frequenca_mesatare;
int16 PWM_F;
int32 PR2;
[Code] ....
This is with Linux gcc
Code:
typedef struct _a
{
int id;
} a;
typedef struct _b
{
a my_a;
my_a.id = 1; // error: expected specifier-qualifier-list before "my_a"
} b;
I get error: expected specifier-qualifier-list before "my_a"
I must set the id for the kind of struct created inside the struct def because main() will be casting based on this id. Thats how I will know which structure b contains by it's id, there could be hundards of different structs with different values I will cast to the correct one and know it's members by it's id. How do I ?
I wanted to ask if it is somehow possible to do:
Code:
class RaspberryPi: public Singleton<RaspberryPi> {
private:
static const DeviceInfo GPS;
template<typename Register_t>
auto ReadGPS(Register_t& Register) -> void
[Code] ....
There are two limitations I am facing:
First, it seems that anything that is part of a struct cannot be a compile-time expression. It's a nice way to group information, so it would be nice to have.
Secondly, it seems that all compile-time expressions cannot be inside a class (at least according to VC++), which means I have to move them to global level, but while it can be done, I don't really want to do it, because it's a platform detail.
In this case, static type dispatch would be nice to have because I have a function
Code:
template<typename Register_t>
auto ReadBus(Platforms::DeviceInfo Device, Register_t& Register) -> void {
switch (Device.Bus)
[Code] .....
There are two types of registers. With runtime dispatch, I get disgusting errors such as "could not deduce template arguments, blah blah" if some object doesn't have the required interface (i.e., don't have overloads for both register types). So the workaround would be to add two overloads and use something like asserts to stop invalid code from running, but it would be so nice to only allow correct code to compile and not get scary error messages.
I'm trying to create an inventory system in C++ using classes and objects. Here is what I have now
Item.h
#pragma once
#include <iostream>
#include <allegro5/allegro.h>
#include <allegro5/allegro_image.h>
[Code]....
Basically what I want my inventory system to become is this: [URL] Each slot can hold an item.
Basically this inventory system should be able to do what RS Inventory system can do. (Hold items, Use items, Equip Items (No need for moving item))
I'm trying to create a program that rolls a dice a few thousand times and print out how many times it lands on each face and then print out a graph using x's as a visual representation using classes.
output looks like this:
1 --- 2000 xxxxxxxxxxxxxxxxxxxxxxxxx
2 --- 1950xxxxxxxxxxxxxxxxxxxxxxxx
.
.
6 --- 2050 xxxxxxxxxxxxxxxxxxxxxxxxxxx
I need a method called int count(int face) inside my class that returns the number of times a particular face has appeared, I just don't know how to incorporate this. I think I should use a constructor and destructor but i'm new with those and knowing when to actually use them.
Here is what I have so far that shows how it should look when printed, just struggling to convert using a class.
#include <iostream>
#include <vector>
#include <cstdlib>
#include <ctime>
using namespace std;
[Code]....
I am getting a compilation error from the code below. It is when i am naming a variable with my user defined type.
#include<iostream>
#include<cstring>
#include<cstdlib>
using namespace std;
class person {
[Code] .....
C:Dev-CppTRIAL.PASS.!!!.cpp In function `int main()':
66 C:Dev-CppTRIAL.PASS.!!!.cpp expected primary-expression before "p"
66 C:Dev-CppTRIAL.PASS.!!!.cpp expected `;' before "p"
74 C:Dev-CppTRIAL.PASS.!!!.cpp `p' undeclared (first use this function)
(Each undeclared identifier is reported only once for each function it appears in.)
83 C:Dev-CppTRIAL.PASS.!!!.cpp `X' undeclared (first use this function)
I have to enter the Instructor ID and invokes getFees to find the fees of the given instructor. Then it will displays the message that shows either the fees or "No such instructor ID" if not found. the function prototype is
double.getProfessionFees(string);
#include <iostream>
using namespace std;
const int DECLARED_SIZE = 7;
int search(const int a[], int number_used, int target);
struct InstructorType
[Code]....
I'm working on a program where I have a vector full of <myClassType> structs.
I'm trying to insert items into a vector, searching first through the vector to make sure the value isn't already in the vector before inserting it. The "find" function isn't working properly.
I keep getting C2678 "binary '==': no operator found which takes a left-hand operand of type "myClassType" or there is no conversion errors in Visual Studio 2010.
I know it's something having to do with the find function and my iterators, but I can't, for the life of me, figure out what it is.
I've tried switching to const_iterators, but I get the same error message.
void foo::insert(const myClassType& en) {
vector<myClassType>::iterator it;
vector<myClassType>::iterator it1;
it = find(Table.begin(), Table.end(), en.memberOne);
[Code] .....
I am having problems with my function definition of a function that should return a structure value.
This is the error I get compute.cpp(9): error C2146: syntax error : missing ';' before identifier 's_advertisebus'
The error is on the line where I start my function definition typing my function type as a structure. A long time ago in c the keyword struct is used with the structure type like struct s_advertisebus s_readadbus(). I tried it both ways but I got errors.
// struct.h
#ifndef STRUCT_H
#define STRUCT_H
struct s_advertisebus {
int nnumberofads;
float fpercentused;
[Code] ....
I am trying to make a automated menu. It shows there are no syntax errors but when compiled it says cannot convert choice from type into to menuItemType. I am not sure what I did wrong. Here is the code
Code: #include <iostream>
#include <string>
#include <fstream>
using namespace std;
struct menuItemType
{
string menuItem;
[Code]...
Code:
class T
{
enum E { }
struct S { }
interface I { }
delegate void D();
class C { }
}
[code]....
All of the above are possible except the constant field of a type that is a struct. I can see why the non-string reference types would default to the only literal expression they can represent - null - and if I'm not mistaken the default value of a struct is an instance of the struct with all its fields set to their default value, but why is it that a const struct field is not possible? is there a reason why or is it just the way c# was written? oh and by the way, what's the idea of allowing enum types to have a default constructor?
This is a c++ Code. I want to read a address to a pointer. When I try to do so it generates an error. I did is >> obj1[0].contentAdress; in main.
struct node3{
node3(){
nextContent = NULL;
for (int i = 0; i<1020; i++)
content[i] = '';
[code]...
no operator found which takes a right-hand operand of type 'node3 *' (or there is no acceptable conversion)
I am trying to compile the files below. The PosLin.cpp contains the SurTriAuto and SurTriPosRotAndQ functions below. Before adding SurTriPosRotAndQ, it compiled fine, but when I added SurTriPosRotAndQ, I am getting "invalid use of incomplete type ‘struct PosRotAndQ" error messages
I was thinking I could try moving SurTriAuto and SurTriPosRotAndQ to PosLin.h, but since they return "T*", I'm not sure what to do
I have a "t.h" file
namespace TNS
{
class T
{
[Code]....
when I add "include Pos/PL.h" to geopar.h, I get an error saying v.hpp is missing, where v.hpp is part of a 3rd-party software and it is already in my directory
Does putting a ref when passing a struct to a parameter work? Say i have this code
struct struct1 {
public int i;
public void show() {
Console.WriteLine(i);
[Code] ....
The output doesn't change. The result is
0
100
500
0
I've been reading the tutorials on Friendship and Inheritance [URL] ..... but I still don't understand why I can't access members of the same struct type.
bool wordBeginsAt (int pos) {
if (pos == 0)
return true;
///use the 'message' string
Message go;
return isAlphanumeric(go.messageText[pos]) && (!isAlphanumeric(go.messageText[pos-1]));
}
The code above is located in a source file, where the function isAlphanumeric passes a char value, and Message is the struct containing the string I want to access. Below is the declaration of the struct and string located in the corresponding header file.
struct Message{
.
.
.
private:
std::string messageText;
};
My frustration comes when I try to call and assign messageText like the tutorial does to its private members, but I keep getting an error saying I can't access the string because it is a private member. Is there a way to access the string without having to pass it through the function wordBeginsAt?
Why I do have this error message?
1>------ Build started: Project: TMA04, Configuration: Debug Win32 ------
1>TMA04.obj : error LNK2019: unresolved external symbol "double __cdecl getFees(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (?getFees@@YANV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z) referenced in function _main
1>C:UsersEvgericDocumentsVisual Studio 2010ProjectsTMA04DebugTMA04.exe : fatal error LNK1120: 1 unresolved externals
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========