I wrote the following program, it can be compiled and run, but there is warning saying that if virtual function is defined, there should be a destructor. How to do that I tried many different ways I can thought of, but none of them works.
#include <iostream>
using namespace std;
class cell_c {
public:
double p;
cell_c() {p=1;}
virtual void print() {cout<<p<<endl;}
[code]....
class Parent{
public:
virtual int width();
virtual int height();
int area(){return width()*height();};
[Code] ....
I want to overload pure virtual function from 3rd party SDK class to put my debug messages like that:
errorStatus aXsaction(){printf(_T("
abort transaction"));transactionManager->abortTransaction();}
#define transactionManager->abortTransaction() aXsaction()
But compiler complains on the minus sign:
error C2008: '-' : unexpected in macro definition
Is it possible to trick the compiler?
I am trying to bend my head around polymorphism but I can't figure out how to use the virtual method properly. I have the following superclass:
Code: class comparable
{
public:
comparable();
virtual bool compare(comparable &other)=0;
}; and the subclass:
Code: class score : public comparable
{
public:
score(string player,int highscore);
bool compare(comparable &other);
string name;
int highscore;
};
My problem is that I do not know how to define the virtual function compare in the subclass score:
Code: bool score::compare(comparable &other){
if(this->highscore > other.???){
...
}
}
How do I tell the compiler that the type is of score?
Assume this class:
class GenericTrafficLight {
public:
virtual enum LightState;
void setLightState(LightState newState) {
currentState = newState;
}
private:
LightState currentState;
};
And this deriving class:
class FuturisticTrafficLight : public GenericTrafficLight {
public:
enum LightState {
LIGHT_STATE_RED = 0,
LIGHT_STATE_YELLOW = 1,
LIGHT_STATE_CYAN = 2,
LIGHT_STATE_GREEN = 3
};
};
This yields this error: "C2911 (...) cannot be declared or defined in the current scope" in the deriving class's enum definition.
have a look-
class Base
{
private:
{
[Code].....
my question is why we can't directly call the member function of the desired class instead of using virtual function.
***********same program using virtual keyword*******************
class Base
{
private:
{
[Code].....
Why we generally prefer the 2nd one i.e with virtual keyword. why we can't directly call the member function of the desired class instead of using virtual function...make me understand this point..
What I'm trying to do :
struct foo {int x; int y;};
foo function_example(int x, int y) {
foo temp;
temp.x = x;
temp.y = y;
return temp;
}
Works as is, however when I try doing it through seperate class files :
//header file for class example_class
struct foo {int x; int y;};
foo function_example(int x, int y);
//source file for example_class
foo example_class::function_example(int x, int y) {
foo temp;
temp.x = x;
temp.y = y;
return temp;
}
I get an error telling me that foo is undefined, and that declaration of function_example(int x, int y) is incompatible with the declaration of it in the header file.
I have this header file called Shape.h containing these function declarations. and a Shape.cpp which contains the body of the function. I am not showing it since it is not needed.
//This is from Shapes.h header file
#ifndef SHAPES_H
#define SHAPES_H
#include <iostream>
[Code]....
I have this unfinished Main.cpp because the third line "JuanSanchez::Circle *pCar = new Circle; " is giving me a compiler error "error C2061: syntax error : identifier 'Circle' "
#include "Shapes.h"
int main()
{
const int arrayIndex = 4;
JuanSanchez::Shape *myShape[arrayIndex];
JuanSanchez::Circle *pCar = new Circle;
}
What Could be causing this error?
I have a function, int teleport_to_game(int,float,float); in my class. My question is should I change the int to define a function to a different type?
View 2 Replies View RelatedI'm making my way through most of this assignment that I have, but now it seems like I've run into a bit of a roadblock. The issue that I'm having is not being able to printf a series of ints that I thought I had previously defined in another function. I don't want to clog up this post with the entire code, so I'll just post one function that defined an int to give an example. I will upload the whole thing upon request however.
Code:
#include <stdio.h>
#include <stdlib.h>
//Prototypes
int AGrade1(int* grade1);
int AGrade2(int* grade2);
int AGrade3(int* grade3);
[Code] .....
I've tried many many things, but I just cant figure it out. This is what it's supposed to look like.
Assignment Grades:
18 12 17 15 20 13
20 18
I would like to make a handler for input events, but not be required to define all the functions.For example, if I had
void mouseDown(int button,vec2 pos);
void mouseUp(int button,vec2 pos);
static void mouseStateHandle(int button,int state,int x,int y) {
switch(state){
case DOWN:
[code]....
in the 'mouseStateHandle' function? I don't know enough about C++ to be able to come up with a solution.
I defined a virtual class and three other classes based on it. I want to use them like this:
int main() {
Dirichlet_t D;
Neumann_t N;
Cauchy_t C;
PDEBoundary_t * B1=& D;
PDEBoundary_t * B2=& N;
PDEBoundary_t * B3=& C;
[Code] .....
but I got two major errors
1: "object f abstract type is not allowed" error.-----why not?
2: "the derived class must implement the inherited pure virtual method"-----Did't I?
I'm currently making a game and what happens is that during runtime, it suddenly closes and a message is shown in the console saying "Pure virtual function called at runtime".
Here is the code: [URL]
The problem seems to occur somewhere between lines 662 - 695. And it seems to only happen when the size of the vector reaches 1.
I'm using a library in my code in a file called "my_signal.c". In this file I've defined this function:
Code:
Sigfunc * signal(int signo, Sigfunc *func){
struct sigaction act, oact;
...
}
Since the signal function is also in file signal.h and I included it in "my_sygnal.h" file, I'm wondering why the compiler did not say anything about this "double declaration" of the function with the same name.
Is there a way to call a function whose name is defined in a file-stored-list?
In other words: The caller doesn't know in compile time the name of the function.
I'm not talking about polymorphism.
The problem is: I have a list of function names stored in a file, that may change every now and then, and I'd like to call them in the sequence they appear in that list.
Instead of this:
#include <iostream>
struct Object {
int size; // Want to avoid this because size is (almost always) constant
Object (int s): size(s) {} // for every Object subtype.
[Code] ....
I want this:
#include <iostream>
struct Object {
virtual int getSize() const = 0;
};
struct Block: Object {
int getSize() const {return 5;} // always 5, except once in a blue moon it may change
[Code] ....
The Decorator Pattern works (getSize() can then return 6) but it is a poor choice for my program because it will cause more problems (due to many containers holding its old address, among other things. Any way to achieve this without any change of address, and without creating new storage somewhere, either inside the class or outside the class (too much responsibility to follow that stored value for the rest of the program just for this rare change, and creating a data member uses up too much memory for the many, many Block instances)?
Let's look at this simplified code, it gives compilation error
#include <iostream>
using namespace std;
class A {
public:
void showInfo() { cout << " This is an instance of A" << endl; }
[Code] ....
Without using pointer, how to make this works?
I want to return value from user defined function to main.
Code:
#include <stdio.h>
int mult ( int x, int y );
int add(int x, int y);
int loop (int y);
int main() {
[Code] ......
I have been trying to compile this program for 3 days. he subject is my error. I know it has something to do with including the cpp file with the header file however my textbook says this is what I must do in order to use templates. I have tried 2 compilers Code Blocks and Microsoft Visual C++ express 2010.
Here is my code:
header file
#pragma once
#ifndef _NODE
#define _NODE
template<class ItemType>
class Node {
[Code] ....
I have found that when I dump a C++ object from memory to a file - it seems that there is a misplacement of the last Virtual-Function-Table pointer - in that appears at the beginning. The result is that the gdump information based on this object dump (using green hills) is incorrect. I copied the contents of the gdump information below. The executable is compiled in linux.
Basically MEIO::CameraStatus contains an item that relates to its parent class (line 188). Then it has 18 items that are all Diagnostics::EventsCounter items. Now for each Diagnostics::EventsCounter item there is a Virtual-Function-Table Info Pointer as its last item. All is fine and good except that the last item of MEIO::CameraStatus which is _selfReset is missing its last item of 4 bytes (which is the Virtual-Function-Table Info Pointer ). On the other hand - right before the first Diagnostics::EventsCounter item ("_vidErrors") - there is an extra 4 bytes which happens to be the Virtual-Function-Table Info Pointer. As I said the gdump information file does not see this.
Why the object memory "moves" the last Virtual-Function-Table Info Pointer to the beginning (right before _vidErrors) and is there a way to "fix" this?
///////////////////////////////////////////////////////////////////////////
"MEIO::CameraStatus" val:0x000002f0 ind208,-1) Struct-Begin Info
188: "" offset 0, Parent-Class Private Info C++ Struct ref = 114
189: "_vidErrors" offset 160, Member Info C++ Struct ref = 128
190: "_vdiErrors" offset 480, Member Info C++ Struct ref = 128
[Code] .....
I'm writing a class "Property" for a program that manages different types of properties. This is my .h for y base class. I was trying to write a virtual void function to convert different children classes to strings that can be displayed, but Xcode is freaking out.
I had it as:
virtual void toString()= 0;
and it gave me an error message: "Virtual can only exist in non-static member functions" and "field has incomplete type 'void'"
I changed it to:
virtual string toString() = 0;
and the error message didn't change.
Is this an issue with Xcode or did I do something wrong? Even after changing it to string it told me that it "has incomplete type 'void'"....
Write a program using user-defined function which is passed a string and that function should cycle the string.(Do not use any string related functions). E.g.
If the string is : Chetna then it should print as Chetna, hetnaC, etnaCh, tnaChe,naChet, aChetn
Ans.
#include <iostream>
using namespace std;
char swamp(char a[], int x) {
for(int k=0; k<=x; k++) {
char l= a[x]; a[x]= a[0]; char p=a[x-1]; a[x-1]=l;
for(int i=1; i<x-2; i++) {
[Code]...
The output I'm getting here just counts every letter in the sentence and counts them as vowels. I'm trying to make the user defined function return the amount of vowels within the sentence.
#include <iostream>
#include <iomanip>
#include <cmath>
[Code].....
We had to write a "selling program for computers, laptops and tablets", which I did but for the extra credit, we have to have those three points in the application and I have tried but how to do the "extra credit" part, which I really need.
1.) A loop to prompt the user if they would like to place another order
2.) At least one user-defined function
3.) An enumerated data type, array or struct (structure)
I did one of these three, it's a "DO WHILE" loop asking users if they want to make another order, it's right at the beginning of the code.
Code:
#include <iostream>
#include <string>
#include <iomanip>
#include <fstream>
using namespace std;
double desktop();//function prototype
double laptop();
double tablet();
[Code] ....
im tasked with creating a linear search script using functions on a 10 element array. the elements are to be supplied by the user as is the search target.
I understand how to create the array and gather that information from the user as well as howto set a variable for "target", this is what im calling it. Those two parts are simple enough.
I am not fully understanding the calling of an array in a function as a pointer. i semi understand the use of a pointer and howto call a normal pointer in a function. i also understand that an array is nothing more then a "special" pointer with a set of consecutive address blocks for the size of the array.
My first user defined function is simple enough
Code:
ReadArray(int A[], int size){
int i;
printf("Please enter %d integer numbers separated by spaces:
", size);
for (i = 0; i < size; i++)
scanf("%d", &A[i]);
}
Sso nothing out of the ordinary there. that should be a standard for loop and use of scanf, sadly prof has not covered ssanf or any of the other options so i am stuck using scanf for now. maybe someday down the line in a other program or after this course ill get the chance to learn about better options for gathering data from the user.
I am confused as to my next function:
Code:
void SearchArray(int A[], int target, int size);
I've not written any code here yet as im not sure if i should call the A[], or *A for the first type of the function?
If i call *A do i then use something like this for my search:
Code:
for (*A = 0; *A < size; *A++)
if (*A < target) or use A[] insteadA?
Code:
for (i = 0; i < size; i++)
if (A[i] = target)
I am attempting to implement function pointers and I am having a bit of a problem.
See the code example below; what I want to be able to do is call a function pointer from another pointer.
I'll admit that I may not be explaining this 100% correct but I am trying to implement the code inside the main function below.
class MainObject;
class SecondaryObject;
class SecondaryObject {
public:
[Code]....