I created a simple program to understand it
class TestClass {
private int x = 10;
TestClass a = new TestClass();
[Code].....
I know this is recursion but how do the compiler do this? How can it call itself when it hasnt even completed initializing every object it has? Why do VS allow this?
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).
I'm having some difficulties in understanding the topic which I stated above.
View 5 Replies View RelatedJust a few moments ago i was just doing foolish things in c++ and discovered something new. Though some of you might have known this, for those who dont know, take a look at the follwing 2 small programs,
#include <iostream.h>
#include <conio.h>
void main();
void loop()
[Code]....
so here is my problem. i think u wud have figured out what m trying to do above. am actually calling the main() of the class and from there, i want to call the usual main... the problem is, during A.main()'s run, if i refer to main(); , that call represents itself, that it, it is like it calls itself. How on earth can i call the outside main?
class abc {
public:
int i;
abc * foooo;
};
How do you call * foooo? Say I create:
abc a;
* foooo would have some values for int i.
To get int i of *foooo, I tried a.foooo.i, which doesn't work. How do you call it?
I'm trying to call a function on a derived class that's in a vector of it's base class. I've made the code really simple for illustration purposes:
class Sprite {
virtual void update();
}
class Enemy : public Sprite {
virtual void update();
[Code] ....
I want to be able to just call update() on the items in the vector and the derived class update() functions be called. Currently, it always calls the Sprite update, which makes sense, but it's not what I want. Is there a way to call the derived update function without knowing the type of the derived class?
Im currently working on a class assignment and the pseudo code containing the instructions that I need to complete list:
//--------------------------------------------------------------------------------------------------------------
// CTOR: Point()
//
// DESCRIPTION
// Default constructor. Initializes the point to be at the origin (0, 0) and the color to black = (0, 0, 0).
//
// PSEUDOCODE
// Call Init() and pass 0, 0, 0, 0, and 0 as the parameters.
//--------------------------------------------------------------------------------------------------------------
My code for this is:
Point::Point(){
void Init(0, 0, 0, 0, 0);
}
The code I wrote for the function Init is here:
Point::Init(int mX, int mY, color mColor){
mX = 0;
mY = 0;
mColor = pInitColor;
}
My problem here is that whenever I try calling this function in the point class, I get an error next to void Init saying incomplete type is not allowed. Also visual studio is telling me that it expects a ')' after my first zero in that line.
Right now I have code
#include <iostream>
using namespace std;
class Rectangle {
private:
double width;
double length;
[Code] .....
it gives error ...
I'm still working on my process API, as in my previous posts. Right now I'm trying get my class portable so I can use it for any language/compiler by using a factory design pattern. I'm having problems figuring out how to call the methods properly from my interface pointer in my factory class without causing a segmentation fault.
Code: main.cpp
Code: #include "exports.h"
#include <iostream>
using namespace std;
[Code]......
// Program to calculate fine using class.
#include<iostream.h>
#include<conio.h>
#include<stdio.h>
#include<string.h>
class library {
long bookid;
char bookname[25];
[Code] ....
In the above program, how do I call the diff. constructors in main?
In the following code example of the State Design Pattern, in the main code at the bottom it defines an instance of class Machine, and then calls Machine::off;. Why doesn't it instead call fsm.off;?
Machine fsm;
Machine::off;
Then I tried imitating that by adding a class Abba, and then doing:
Abba a;
Abba::DoStuff();
but that didn't work. Why?
Full code example:
// StatePattern.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include <iostream>
using namespace std;
class Machine {
class State *current;
[Code] ....
class IFoo {
virtual void Bar() = 0;
};
class FooAbstract {
virtual void Bar() {}
[Code] .....
How to call the Bar() method from FooTemplate in FooDerived::Bar()?
If I have an array of some class, and that class has const members, is there some way I can call a custom constructor on elements of the array?
I can't seem to reinitialize an element in foos in the example below. A thread on stack overflow mentioned the copy constructor show allow it, but I get "no match for call to '(Foo) (Foo&)'" when I try it.
Code:
class Foo {
public:
Foo();
Foo(int x, int y);
[Code] .....
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]....
I have a class 'A' which is almost perfect for my needs. Class 'B' uses class 'A' I've now designed Class 'C' and Class 'D' and noticed that there is a good chunk of code in class 'B', 'C' and 'D' for using Class 'A' is duplicated. I've separated out this code in specific, standalone functions in each of the classes. Now I'm wondering where this code should go. At the moment, the functions are duplicated in the three calling classes (B, C and D). Placing the functions into class 'A' would break the single responsibility principle. Inheritance to add functionality would likely break both SRP and LSP. The one that seems that it may work is composition.
However, Is designing a complete class just for a few functions over kill?
Would it be valid for classes 'B', 'C' and 'D' to access both the new class 'E' (which would depend on A) and the old class 'A' (which would have to be the same instance as the instance in the new class 'E'), or should the new class 'E' provide sufficient functionality so that Classes B, C and D don't need to access Class A directly? It would seem that its then an incomplete interface of the original object with additional functionality (ie, incompatible) Or should I do it a completely different way?
I am using a dll written in FORTRAN to do some calculations and here is how I have set up the program. I have created following files:
C++ source files:
main.cpp
File1.cpp
Header Files:
Datamain.h
DataFile1.h
[Code]....
Here are my questions:
1) I actually want to call Sub2dll from the main program. But the above program does not build and it gives me the following error: In function 'int main()': Sub2dll was not declared in this scope.
When I build this program with the call to Sub2dll in main commented out and instead put that call in File1::Setup function things build well and runs giving the answer expected. How can I make the call to Sub2dll from main.
2) I am including "Datamain.h" in main. However when I build it with out the declaration int Datamain::Index; in main, it gives me the following error: undefined reference to Datamain::Index When I add that declaration to main the error disappears.
I am usiing Code::blocks with MinGW compiler. I have not put the argument list for the subroutine calls since there were not errors in that part.
I have this sample code, that calls a function in a DLL. The function Callback is provided to the DLL as an argument, in order for the DLL to notify my program of relevant changes.
sample:
#include <iostream>
#include <conio.h>
#include <windows.h>
#include <winbase.h>
#include "TcAdsDef.h"
#include "TcAdsApi.h"
using namespace std;
void _stdcall Callback(AmsAddr*, AdsNotificationHeader*, unsigned long);
[Code] ....
I would like to change this code, so that there is a Main class that opens the connection and there are several separate classes (as below) that register themselves for a specific variable and get notifications if that value is changed. The reason for this is that I want to get several notifications for several independent events and I don't want them to mix. I figured this should look something like this:
class.h
#ifndef INACLASS_H
#define INACLASS_H
#include "Main.h"
class InAClass {
public:
InAClass(Main* mainClass, std::string iolocation);
[Code] ....
Unfortunately this gives me an error:
error: cannot convert 'InAClass::Callback' from type 'void (InAClass::)(AmsAddr*, AdsNotificationHeader*, long unsigned int)' to type 'PAdsNotificationFuncEx {aka void (__attribute__((__stdcall__)) *)(AmsAddr*, AdsNotificationHeader*, long unsigned int)}'
At first I thought this was because I don't have the namespace "using namespace std;" on top, but then I should be able to find something that specifically needs to come from the std namespace and is not marked as such. I don't want to rule the option out, but so far I could not find anything like that.
An alternative explanation might be that the Callback function needs to be global, but if I make it global, how can I distinguish between several Callback functions?
So I am wondering how I would go about calling a function for all instances of an object. I tried googling it, but all I saw was solutions like making an array of pointers to the objects. What if I don't know how many objects there will be? Isn't there an easier way?
View 19 Replies View RelatedHow do I call these functions from Mechanical.h???
Mechanical.h
#ifndef MECHANICAL_H_
#define MECHANICAL_H_
class statics { public:
template<class T> struct Inertia_types {
T Rec(T _x, T _y);
T Tri(T _x, T _y);
[Code] ...
I am trying to create templated functions which I can apply all data types to except for strings and other types such as wchar. Am I also writing these correctly? This is my first attempt ever doing this.
Every time I try to use the function SaveNewCD, it doesn't write to file correctly. It writes the ~, three characters, then goes into an infinite loop.
#include<iostream>
#include<fstream>
using namespace std;
int SaveNewCD();
int OpenCD();
int main() {
char ArtistName[25];
[Code] .....
I am trying to call a function through a variable
The error
|error: no match for 'operator=' (operand types are 'std::string {aka std::basic_string<char>}' and 'void')|
|warning: statement has no effect [-Wunused-value]|
||=== Build failed: 1 error(s), 1 warning(s) (0 minute(s), 0 second(s)) ===|
#include <iostream>
#include <fstream>
[Code].....
I am trying to use ofstream to write in a txt file in a function called recurrently. for a simplified example:
void func_write(double x) {
ofstream myfile;
myfile << "the result = " << x << endl;
} int main() {
ofstream myfile;
[Code] .....
To this stage, it does not work, because the myfile in func_write cannot write in the txt file opened in main function. I don't want to open, append and close the txt file each time the function is called, that will take more time to execute all (imagine with 500 calls).
Having issues calling my arguments from my templates, when i declare x and n in the main it comes up with errors
code below:
#include <iostream>
#include <cmath>
#include <cstring>
#include <string>
#include <string.h>
using namespace std;
int intInput1, intInput2;
[code].....
I want to call the array from one function to another all function not a main function
View 2 Replies View RelatedAllow users to enter their name and favorite saying in a single method that gets invoked two times. If I can only return one value at a time, how am I suppose to get name and favorite saying out of UserInput()?
static void Main(string[] args) {
string displayName, favoriteSaying;
DisplayInstructions();
Console.WriteLine();//readability
[Code] ....
I want to update a label from Form2. When I click on the button on Form 2, the textbox on Form2 should update the label on Form1 and take me to a certain website. What ever URL is typed into the textbox on Form2 is what website URL the label on Form1 will take me to. The label on Form1 can say something such as You can check out my website here!!! and when they click on the saying it takes me to their website.
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