C++ :: Virtual Can Only Exist In Non-static Member Function - Field Has Incomplete Type Void
Dec 5, 2014
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'"....
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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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Nov 30, 2013
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?
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May 10, 2014
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)?
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Oct 7, 2014
How to initialize a static member of a class with template, which type is related to a nested class?
This code works (without nested class):
#include<iostream>
using namespace std;
struct B{
B(){cout<<"here"<<endl;}
};
template<typename Z>
[Code] ,....
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Aug 27, 2014
I need to keep a static variable in a member function of a class that I have many objects of. I've had some trouble with it, and when I read up I found that such variables are static across all instances. Is there any way around this?
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Mar 8, 2014
What am I doing wrong with static members and methods here?
compiler errors:
1>test.obj : error LNK2005: "private: static int Test::count" (?count@Test@@0HA) already defined in main.obj
1>c:usersjamesdocumentsvisual studio 2013Projectsstatic_testReleasestatic_test.exe : fatal error LNK1169: one or more multiply defined symbols found
test.h
#ifndef TEST_H_
#define TEST_H_
class Test {
[code]....
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Aug 19, 2014
I have the following problem: I am using NLOpt for optimization. The API provides functions to set the objective. This is done as follows:
double objective(const vector<double> &x, vector<double> &grad, void *data)
{
return x[1]*x[0];
}
int main(){
nlopt::opt opti(nlopt::LD_MMA,2);
opti.set_min_objective(objective,NULL);
vector<double> x(2);
[Code]....
Now I want to make the function objective a member of a class:
class Foo {
public:
double objective(...){..}
};
How can I give this method to opti.optimize? If I make objective static I can use
opti.optimize(Foo::objective,NULL);
but I do not want to have a static member. Is it possible to create an object of type Foo and give it to opti.optimize?
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Jul 20, 2013
Say you had:
class Foo{
public:
//...
void funky();
[Code] .....
Would each instance of Foo create a new counter variable, or would it remain the same for all of them, i.e. baz.funky() would always use the same counter variable? What if the class was a template?
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Jan 16, 2012
I am experiencing some errors with my first c++ program. im getting some compilation errors that i cannot figure out.
In file included from w2.cpp:7:
Fraction.h:17: error: variable or field 'enter' declared void
Fraction.h:17: error: expected primary-expression before 'struct'
Fraction.h:18: error: variable or field 'display' declared void
and so on ..........
Code:
#include "fraction.h"
//using namespace std;
/*
int main() {
struct Fraction fraction;
cout << "Fraction Simplifier" << endl;
cout << "===================" << endl;
enter(&fraction);
[Code] .....
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Mar 29, 2014
I'm creating a payroll program and here is my code
Code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define REPORTHEADING1 " Employee Pay Hours Gross Tax Net
"
#define REPORTHEADING2 " Name Rate Worked Pay Due Pay
}
[code]....
The errors I get are: variable or field PrintSummaryReport declared void in function voidPrintSummaryReport... cannot convert FILE to const car for argument to int printf(const char*...) which is for the following lines
Code:
printf(reportFile,REPORTLINEFORMAT1,fullName,payrate,regHours,gross,fedtax,
ssitax,netpay);
printf(reportFile,REPORTLINEFORMAT2,ovtHours,statetax,deferred);
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Sep 17, 2014
Why I am getting this error
error: variable or field createBinaryFile declared void
void createBinaryFile(std::fstream&, std::ifstream&);
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Mar 28, 2014
I'm creating a payroll program and here is my code
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define REPORTHEADING1 " Employee Pay Hours Gross Tax Net
"
#define REPORTHEADING2 " Name Rate Worked Pay Due Pay
[code]....
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Apr 25, 2013
I am doing fixed point implementation in c++ which is done by the following code
#ifndef __fixed_point_header_h__
#define __fixed_point_header_h__
#include <boost/assert.hpp>
#include <boost/static_assert.hpp>
#include <boost/operators.hpp>
#include <limits>
[Code] ....
I am getting the error ambiguous overload for âoperator<â in âbeta < ((-5.0e-1) * pi)â
I know the problem the static member function cannot access the members and objects of structs. am i right?
and how to solve this problem, do i need to implement the cossin_cordic function as a non member function.
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Oct 10, 2014
On running the following codes I'm getting these errors. I'm using Code Blocks 13.12
void view(string); //error: variable or field 'view' declared void & error: 'string' was not declared in this scope
void customer()
{
char ch;
[Code]....
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Sep 11, 2013
What are the workarounds for accessing the non-static member variables of some class(Say A) inside static member functions of another class(Say B)? I am coding in c++. Class A is derived with public properties of class B. Any pointers?
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Feb 10, 2013
I am modifying a set of static variables inside of the class's member function. The static variables are private. An example of what I'm doing is as below,
utilities.h
-----------
class utilities {
private:
static int num_nodes;
public:
void parse_details(char* );
[Code] ....
I get a compilation error in the function void utilities::parse_details(char* filename)
which says: undefined reference to `utilities::num_nodes'
compiler: g++
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May 8, 2013
I am trying to get a program to take two files and place them into a third file. I have searched all over this website looking for a solution and i can seem to find one.
My issue is that i keep getting an error 'incomplete type is not allowed' as well as 'no operator matches these ">>" these operands.'
#include<iostream>
#include<string>
#include <sstream>
using namespace std;
int main() {
string filename1;
[Code] .....
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Jul 19, 2012
So, I ran into the above error. I can't post the actual code, but here is the setup... I have four classes: A, B, C, and D.
A.hpp
Code:
class A {
public:
virtual void foo( D& bar );
[Code] .....
In A.cpp I implement foo and use bar in a similar manner as shown in class C. The difference here is that in A.cpp I also include the header for the D class. I am a bit confused why I can pass bar to B::foo() and that works fine, but if I try to access bar in C::foo, I have issues. Currently I am just including D.hpp in C.cpp.
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Sep 30, 2014
I have an enum like:
Code:
typedef enum mac_type_e{
STATIC_MAC,
BLACKLIST_MAC
} mac_type_t; and I want to use this type in a structure that's declared like:
Code:
typedef struct lan_mac_s {
UINT16 lanmacid;
enum mac_type_t lan_mac_type_pp;// user mac type per port, 20 mac_type_t array, 0 = static, 1 = blacklisted now,
The compiler tells me:
Code:
incomplete type is not allowed
enum mac_type_t lan_mac_type_pp;// user mac type per port, 20 mac_type_t array, 0 = static, 1 = blacklisted
But if I remove the preceeding "enum" keyword, it compiles fine.
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May 26, 2014
When declare and assign an instance of a user-defined struct in a function. And the struct (theStruct) is not declared in the same header file as the function (theFunction). Like this:
files:
"A.h": declares the struct in a class (theClass)
"A.cpp": implements the struct
"B.h": declares the function
"B.cpp": implements the function, error here
I think making the instance (inst) a reference might solve this. But the instance is assigned to a return value from a function (returnFunc). Like:
void theFunction() {
...
theClass::theStruct inst = returnFunc(...);
//returnFunc() returns an instance of theStruct
//the error is at 'inst'
...
}
What do you think?
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Apr 18, 2015
The code below is supposed to be a program that allows the user to enter in 2 matrices and add them together, and gives an error when they're not the same dimensions.
The error I'm getting is on line 11 of MAIN.CPP and is saying "The Variable has incomplete type 'Matrix'".
MAIN.CPP
#include <iostream>
#include <vector>
#include <string>
#include "Matrix Class Input.h"
using namespace std;
int main() {
Matrix A,B,C;
int r,c=0;
[Code] .....
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Feb 27, 2014
keep getting "deferencing pointer to incomplete type" on the bold lines:
main:
int main(int argc, char *argv[]) {
printf("Please think of an animal. I will try to find out what it is by asking you some yes/no questions.");
struct treenode *root = mkTreeNode("Is it a reptile?
", NULL, NULL);
struct treenode *selectedNode = root;
root->left = mkTreeNode("Does it have legs?
[code]....
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May 21, 2013
Code:
#include "..ObjectsObjects.h"
class Idle;
class Objects;
class Goods;
[Code].....
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Aug 26, 2014
I need a static hash table to keep track of all objects of a particular type that are instantiated in a Qt application but I have never used a template class as a static member object before and I can't seem to figure out how to initialize it. QHash is the hash table class that follows the template convetion:
template<class key, class data>
QString is probably self explanatory.
Example Header:
class MyClass {
...
private:
static QHash<QString, MyClass*> instanceTable;
}
Here is my source that doesn't compile.
Example Source
#include header.h
// using default constructor for table...
QHash<QString key, MyClass* instance> MyClass::instanceTable(); // gives Error below.
// Error in above line is "Declaration is incompatible with QHash<QString, Myclass*>"
I have tried doing it a number of different ways and none of them work. How do you initialize a static template object?
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Feb 21, 2015
I've been writing the math functions for a 3d game and tried compiling it at about 30 functions in. I get this error related to my pointers to my structures. it affects almost everything in all my functions (as youll see by looking at how i do the math in the function below). The compiler gives me the error
"error: dereferencing pointer to incomplete type"
on all my struct Type4D pointers but referencing the values in my struct TypeMatrix4X4 using pointers seems to work fine i think (it doesn't seem to complian explicitly about it. so here is the important code...
one example function
Code:
struct Type4D *MatVecMult4X4RtoL(struct TypeMatrix4X4 *mat, struct Type4D *vec) {
struct Type4D *dest = (struct Type4D *) malloc(sizeof(struct Type4D));
[Code]....
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