Code:
class Base {
public:
int base;
Base(int init=0):base(init){}
virtual ~Base(){}
[Code] .....
Invalid initialization of non-const reference of type 'Base&' from an rvalue of type 'Derived'
What does it mean, and why can't I return the Derived class by value (I'm trying to create an exact copy of Derived).
I am trying to use the Singleton design patterno on Linux, but it is not working:
in the .h I have:
Code:
public:
static ErrorH& Instance();
private:
ErrorH() {};
In the .cpp I have:
Code:
ErrorH& ErrorH::Instance() {
static ErrorH& self = ErrorH();
return self;
}
The errors I get are:
Code:
g++ --g -c ErrorH.cpp -o ErrorH.o
ErrorH.cpp: In static member function "static ErrorH& ErrorH::Instance()":
ErrorH.cpp:9: error: invalid initialization of non-const reference of type "ErrorH&" from a temporary of type "ErrorH"
make: *** [ErrorH.o] Error 1
This code works on Windows, how can I get it to work on Linux?
The error is : invalid initialization of reference of type 'ArrayT<float>&' from expression of type 'const Arrat<float>'...The above errors occur when I tried to do the following code , with operator* overloading :
const ArrayT<float>& b1 = A*A;
ArrayT<float>& c2 = b1*A;// <---- this line makes the error
//b1 is a const ref of ArrayT<float>
//A is just a normal object of ArrayT<float> created by ArrayT<float> A(blah,blah,blah);
The following are the list of operator* overloading :
template <class T>
ArrayT<T>& ArrayT<T>::operator*(ArrayT<T>& b) {blah,blah,blah}
template <class T>
const ArrayT<T>& ArrayT<T>::operator*(ArrayT<T>& b) const
[code]....
I want to use for error multiplication above, but not success.
I dont know what kind of return reference I have to put to override the following derived member function in C++:
virtual SEntityPhysicalizeParams& GetPhysicsParams() override {return ???;}
The place where I should put the return value is marked with ???. SEntityPhysicalizeParams is a struct from another header from which I dont have access to it's source file.
I tried several things but noone seemed to work out and keep getting me either error "function must return a value" or "initial value of reference to non-const must be an lValue".
Here is SEntityPhysicalize where my function is refering to:
struct SEntityPhysicalizeParams
{///////////////////////////////////////////////////////////////////
SEntityPhysicalizeParams() : type(0),density(-1),mass(-1),nSlot(-1),nFlagsOR(0),nFlagsAND(UINT_MAX),
pAttachToEntity(NULL),nAttachToPart(-1),fStiffnessScale(0), bCopyJointVelocities(false),
pParticle(NULL),pBuoyancy(NULL),pPlayerDimensions(NULL),pPlayerDynamics(NULL),
pCar(NULL),pAreaDef(NULL),nLod(0),szPropsOverride(0) {};
[Code] ....
After looking online for a string replace function in C and finding so many examples that go through the entire string twice. First round to find how number of occurances of substitute in string, using that to malloc for a new string to include additional space for replace, then going through the search string again to get all but what's to be substituted out. I feel it's kind of silly to go through the string twice. Therefore, I'm trying to implement my own string replace, that only searches through the string for what's to be substituted, once.
Here is my code:
Code:
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
char *strreplace(char * string, char * sub, char * replace);
}
[code]....
Here is the same code, but with execution + some syntax highlighting: Ideone.com | Online C Compiler & Debugging Tool..It works great, until it gets to grabbing whatever remains in the search string after the last found sub. The realloc throws a runtime error:
Code:
*** glibc detected *** ./a.out: realloc(): invalid next size: 0x00011008 ***
Aborted From my understanding, this is from me going outside of the bounds of the heap and using memory I haven't allocated, or using a free'd pointer. I'm not seeing where either of these are happening in my code, and was wondering what the best way to go about figuring out where the error exactly occurs.
The exercise consists on 3 procedures. We get the information from a .txt like these:
01/03/2011 A
02/03/2011 F
03/03/2011 C
04/03/2011 T
(...)
Simulating a Videoclub database where the letters stand for the type of movie (A=Action, T=Terror, C=Comedy, ...) and the dates they were rented.
a) How many movies from one specific genre have been rented more than 'n' times? The genre and the value 'n' must be entered by the user.
b) How many movies and which genres belong to a certain date? The date must be entered by the user.
c) Print a list that shows the number of times a movie from each genre has been rented.
So far this is what I've got:
Code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAX 100
typedef struct {
int dia,mes, any;
char genere;
[Code] ....
But right now, my main problem is that I can't even debug because i get an error in line 97 --> while (llista[i][j] != EOF) <-- saying "invalid operands to binary != (have 'lloguer' and 'int').
I've tried to cast (int) before "llista[i][j]" but it says that I'm already supposed to get an integer from that.
Say I have 3 classes:
class Player {
public:
virtual func1();
[code]....
Say in my main class, I have a function fight(Player p1, Player p2) and I would like to do something like this in the fight function, given that p1 is the human and p2 is the computer:
//function fight()
fight(Player p1, Player p2) {
p1.func2();
}
//using function fight()
fight(human, computer);
When I compile the program, I got this: error: ‘class Player’ has no member named 'func2()' What can I do to allow p1 to call func2 inside fight()? I'm not allowed to use pointers as the parameter for fight() and have to use the signature fight(Player p1, Player p2).
The compiler creates virtual table for the base class and also for the derived class whether we override it or not.
That means each class has separate virtual table. when we get the size of the each class with out any data members... the size of base is -- 4 bytes(64 bit) and the size of derived is -- 1
The size of base class 4 is correct since it creates the virtual pointer internally and its size is member data + virtual pointer, but it in this case I have included any data members so it has given 4 byts.
But why in case of derived is 1 byte, since it the derived class has overridden the virtual function from base, this will also contains the virtual pointer which will be pointing to derived class Vtable, it the size of the class suppose to be 4 instead of 1 byte.
#include<iostream>
class A{
public:
[Code].....
I have my main.cpp like this:
#include <iostream>
#include "curve1.h"
#include "curve2.h"
using namespace std;
int main() {
Curve1 curve1Obj;
Curve2 curve2Obj;
[Code]...
Base class Score has two derived classes Curve1 and Curve2. There are two curve() functions, one is in Curve1 and other in Curve2 classes. getSize() returns the value of iSize.
My base class header score.h looks like this:
#ifndef SCORE_H
#define SCORE_H
class Score {
private:
int *ipScore;
float fAverage;
int iSize;
[Code]...
You can see that I have used curve1Obj to enter scores, calculate average and output. So if I call getSize() function with cuve1Obj, it gives the right size that I took from user in enterScores() function. Also the result is same if I call getSize() in score.cpp definition file in any of the functions (obviously).
.....
The problem is when I call curve() function of Curve2 class in main (line 23) with the object curve2Obj, it creates a new set of ipScore, fAverage and iSize (i think?) with garbage values. So when I call getSize() in curve() definition in curve2.cpp, it outputs the garbage. .....
How can I cause it to return the old values that are set in curve1.cpp?
Here is my curve2.cpp
#include <iostream>
#include "curve2.h"
using namespace std;
void Curve2::curve() {
cout << "getSize() returns: " << getSize() << endl; // out comes the garbage
}
Can I use a function to simply put values from old to new variables? If yes then how?
In this book, item 3 is about never treat arrays polymorphically. In the latter part of this item, the author talks about the result of deleting an array of derived class objects through a base class pointer is undefined. What does it mean? I have an example here,
Code:
class B
{
public:
B():_y(1){}
virtual ~B() {
cout<<"~B()"<<endl;
[Code] ....
This sample code does exactly what I want. So does the author mean the way I did is undefined?
I keep getting an error "Invalid use of void expression" on line 12.
Code:
#include<stdio.h>
#include<stdlib.h>
void initialiaze_array( int size );
void print_array( int size );
void replace( int num, int i );
[Code] ....
Please consider the following code :
#include <iostream>
using namespace std;
class superclass;
class subclass1;
class subclass2;
[Code] ....
As you can see I want to create a dynamically allocated storage of references to a parent class each of which can then point to a child class, how ever I do not know how to extract the child class out again from that array so i may access its variable b.
So I have a base class, lets call it base. In base I have a virtual function called update(), update just couts "base" then I have a class derived from base called derived;
it has a function called update(), update just couts "derived" then I create a vector called Vec it's initialised like this:
std::vector<base> Vec;
then I add an element into it like this
Derived DerElement;
Vec.push_back(DerElement);
then when I type:
for (int i=0; i<Vec.size(); i++) {
Vec.at(i).Update();
}
It outputs:
Derived DerElement2;
DerElement2.Update();
and it outputs this:
#include <iostream>
#include <vector>
class Base {
public:
virtual void Update() {
[Code] .....
and this is it's output:
Base
Derived
Press any key to continue . . .
I would like to know if there's a way to make a method from a derived class a friend of its base class. Something like:
class Derived;
class Base {
int i, j;
friend void Derived::f();
protected:
Base();
[Code] ......
I have an example where I have a variable belonging to a base class, but I would like to tell the compiler that it actually belongs to a derived class. How can I do this?
// base class: R0
// derived class: R1
// see function SetR1 for the problem
class R0 {
public:
int a;
[Code] .....
I just wondering if a base class can call the overridden function from a Derived class?
Here's an example:
//Base Class H
class BaseClass {
public:
BaseClass();
virtual ~BaseClass();
virtual void functionA();
[Code] ....
So basically, when I am creating a new object of Derived class, it will initialize BaseClass and the BaseClass will call functionA but I want it to call the function overridden by Derived class.
I know that if I call newObj->functionA it will call the overridden function. Right now I want the base class to call the overridden function "this->functionA(); in BaseClass" during its initialization. Is it possible to do that?
I am using visual studio 2012 on windows 7. but, when I have compiled my programs and run them on an older pc to test out its functions, I receive an error saying that the program is not a "valid win32 application." I have even tested this with a very simple hello world console application, but the problem still remains. Where is the error coming from? is the application corrupted during transport? (upload to internet) or are programs compiled on win 7 incompatible with win xp
View 6 Replies View RelatedThe compiler keeps on telling me that invalid conversion from wxBitmap* to wxString on the line with the AddTool function, whiles I do not even try to do such an ambiguous typecast.
wxWidgets 2.9.4
MinGW
gdb
Code:
#include "mainwnd.h"
//namespaces
//other definitions and declarations
CMAINWND::CMAINWND(const wxString& szTitle):wxFrame(NULL,wxID_ANY,szTitle) {
wxImage::AddHandler(new wxBMPHandler);
[Code] .....
I making a simple single number scrambler/encryptor and as I tried to build the console application the following error
occurred:
error: invalid operands of types 'void' and 'int' to binary 'operator%'
The source code is bellow.
#include <iostream>
#include <math.h>
#include <cstdlib>
using namespace std;
int main() {
int nTimer;
int nInput;
[Code]......
I am running code::blocks as my IDE on Ubuntu.
Basically, I have a base class called MainShop and it has 3 derived classes which are SwordShop, SpellBookShop and BowShop. I want the base class to be able to call a function from one of the derived classes but no matter what i do, it doesn't seem to work!
Here is my code:
#include "MainShop.h"
//BaseClass cpp
void MainShop::EnterShop(Hero& hero)
[Code]....
I have two other derived classes, but its basically the same concept. I have a function in one of the derived classes and i would like to call it from the base class. This is one my derived classes:
//SwordShop derived cpp
#include "SwordShop.h"
void SwordShop::soldierShop(Hero& hero)
{
/* some code here*/
}
Base class has an array, whose size is controlled by the derived class.
I can't use the STL and use a 2003 compiler, so things like std::vector and std::array are out. I also can't use dynamic memory allocation.
So I thought of a few options:
1.
template <int N> class myBaseClass { ... int array[N]; ... }
then class MyClass: public myBaseClass<8> ... etc ...
2.
have a int **array in the base and assign in the derived class.
3.
give the base some virtual methods such as int *getArray or even int &getInt for more safety.
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'm having some difficulties in understanding the topic which I stated above.
View 5 Replies View RelatedIf 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] ....
Well, I thought I had this program working but now I'm getting the above referenced compiler error. The program is just a basic user interface. It is for a classwork assignment.
The program is to accept user information as a string, convert it (if needed) to either the int or double variable, and then display the result. I'm using stringstream convert to make the change between types, but I'm not sure if I'm using it right (that might be what's causing the error, I'm not sure). Line 36-37 generates the error.
Code:
#include <iostream>
#include <iomanip>
#include <sstream>
using namespace std;
[Code] ....
Below is my code snippet.I'm getting "Error:initialization from incompatible pointer type" error on line 'int *q = status;'.
Obviously, I'm missing something but has no clue...:(
void findwalls(int *p,int y,int x){
int status[y_count][x_count][4];
int *q = status;
for(int i = 0;i < (y_count * x_count * 4);i++)
*(q + i) = *(p + i);
