I need to use an instance of an object in a header file. The object requires a lot of pre-computation to be created.
I want to assign it to a "static const *NAMEobject*" field in the .h file, once it has been created. I assume that it is better to create it in another file and somehow pass it into the .h file.
I'm working on a grocery store inventory project. One part is to have a shopping cart, where customers can put in up to 20 items. Because there can be up to 20 shopping carts at one time, I want to use a vector inside the cart object to represent all the individual food items.
Here's my code,
Header:
#ifndef CART_H
#define CART_H
#include <vector>
class Cart {
public:
Cart();
Cart(std::vector< int >, std::vector< int >)
[Code] ....
Let's say I am using a library containing classes called class1 and class2 but both classes take three arguments to construct them. eg. class1(int a, int b, int c). and the same for class2
The below is an example of how to lay out the structure in the header and source file if class1 and class2 don't have any arguments in their constructor. But.... I'm not sure how to go about the below to take into account the constructor arguments of class1 and class2.
program.h
struct thestructure
{
thestructure(class1, class2); //constructor.
[Code].....
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?
I have this class:
class Excuse
{...
public string Description { get; set; }
public string Results { get; set; }
public DateTime LastUsed { get; set; }
public string ExcusePath { get; set; }
....}
[Code] ...
When I run it, I do get the messagebox popping up with the correct description, but then nothing happens. When I debug, I see the fields under the UpdateForm() method are set to null.
I'm guessing this happening because it is looking at the 'currentExcuse' that was declared in the form body. I thought however that redeclaring 'currentExcuse' in the method would overwrite this instance or am I wrong?
Do I need an array to make this work?
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.
In 32bit, the object header size is always 8bytes.
In 64bit, the object header size is always 16bytes.
Is this safe to assume or are there situations where the header size can be smaller/larger than the numbers above?(Haven't found anything on this, so I assume no?)
I need to know the exact size of the object header, because I need specifically pad a few classes I wrote to avoid false sharing along cache lines. Just need to make sure I have the sizes correct so I don't pad them wrong!
I have written my program and it works when I keep everything in the header files, and then have my main. I am now splitting them up into implementation files, but Eclipse keeps giving me errors. It gives me error at every opening brace of the constructor and functions. It says on all of them "Redefinition of (name of constructor or method), Previously declared here." What am I doing wrong, because it works in the header file?
#include "KeyValuePair.h"
template<typename Key,typename Value>
KeyValuePair<Key,Value>::KeyValuePair()
[Code] .....
I am working on an assignment in which i have to perform th following task
myClass itsObject1,itsObject2;
itsObject2=5000+itsObject1;
I have defined overloaded operator as follows in the header file but in the cpp file of the class it gives error.
friend vli &vli::operator + (int &a,vli &obj);
How to define it in cpp file of my class?
What is the right syntax for implementing the .cpp of a template class?
Consider this LinkedList.h file:
Code: #include<iostream>
#include"Iterator.h"
template <class T>
class LinkedList {
[Code] ....
How should the implementation for the LinkedList constructor, for example, should look like in the LinkedList.cpp file?
I tried this:
Code: #include "LinkedList.h"
template <class T>
LinkedList<T>::LinkedList<T>() {
// constructor
}
LinkedList<T>::~LinkedList<T>() {
// destructor
}
But the compiler wouldn't accept it.
lets say we have a valid class with full implementation, X. can this class be declared as forward in Y header file:
Code: class X;
class Y{
X* m_X;
}
but still be used as regular in the cpp file?
Code:
#include "Y.h"
#incldue "X.h"
T Y::function(){
m_X->doSomething();
}
visual studio prevents me from doing it , I wonder if the standard also says so.
I wanted to share the value of a variable from Sender Program to Receive after program and want to calculate difference between send and receive. After studying Header file concept I program following three.
Now I am struck. How to to compile? I link all these file. I used following method:
Code:
gcc Sender.c -o Sender Sender.h
gcc Receiver.c -o Receiver Student.h
Then I run Sender and after that Receiver.I per my knowledge, Receiver should give difference but it gives error :
Code:
Receiver.c: In function "main":
Receiver.c:10:42: error: "Send" undeclared (first use in this function)
printf(" Total Receive is %d
",Receive-Send);
Code:
Sender.c
#include <stdio.h>
int Send ;
void main(){
[Code] ....
I have been working a project in C++. I have TTTMain.cpp file that has all the function calls, TTTFuntions.cpp that has all the functions, I have TTT.h file that has all the prototypes and variables and additionally I have Winner.h that has enum class Winner declaration in it. Here is my block of codes:
Winner.h file:
#ifndef winner
#define winner
enum class Winner {
[Code]....
My question is when I compile this gives me error on
Winner gameSquares[] = { Empty, Empty,Empty, Empty, Empty, Empty, Empty, Empty, Empty };
with saying "invalid use of non-static data data member" and It says "Empty was not declared in this scope."
I know calling enum is very very trick.
I am beginner in c++ language. i'm use visual studio 2010 ultimate. the problem is i can't add c++ file(.cpp) and header file(.h).
Here the screenshot : [URL] ....
I made my header file. If cpp file with definitions is in project compiler knows it has to be linked, but if it's not compiler doesn't know. If I include standard library or boost I don't have to manually link cpps. How to do so including my header automatically links cpp? Maybe problem is with something else?I use VS 2013.
View 4 Replies View RelatedMy socket.cpp program got error. it showed "socket.h: no such file or directory". I had put my header file (socket.h) in the same place with my source file.
View 1 Replies View Related1. Write a program the calculates the volume of a sphere.
Use a define to set Pi to 3.14 and a macro for the formula for the sphere.
V = 4/3PiR3.
In main ask for the radius (R).
Pass it to a function where you calculate the volume and return it to main and print the volume in main.
Use float values. (Save this program as you'll need it later.)
Code:
#include<stdio.h>
void fun (float);
main()
[Code].....
Can we put using namespace std; in a header file? Someone told me not to do it, but I don't know why...
View 2 Replies View RelatedI need read a file with header and I wanna print the file in output. How can I do that? I tried but not work..
#include<iostream>
#include<fstream>
using namespace std;
int main()
{
[Code]....
All i want to do is modify a header of a file(.exe file). I just want to do if for fun and see what I can do with it.
View 3 Replies View RelatedI have a class Myclass (for the sake of the example). I have a header file 'space.h', which is following:
#include "Myclass.h"
struct Files {Myclass* new_object, int number};
But turns out in the Myclass.h, I need the struct Files, like so:void function(vector<Files> arrangement);
So I would have to include "space.h" in the Myclass.h, but this way there's going to be a double definition of struct Files, since Myclass.h includes space.h and space.h includes Myclass.h.
Any good/solid example on how to create a header file?
View 2 Replies View RelatedI have written code for a timer. with everything and i want to include this so i dont need to write or copy the reqd code each time. how do i do this?
View 9 Replies View RelatedI wrote a simple date class and could not get it to work until I put all the code in main(). Then it worked like a charm. I have not been able to create a separate .cpp file and get it to work with my existing main().
I tried to follow [URL] which is a closed article, with no success. I tried every combination I could think of and was unable to compile without error. (Linux Mint 17,code::blocks 13.12, G++ 4.8.2). I did finally get it to work by putting *all* my code in the .h file and #including the .h file (and nothing else) in the .cpp file. This is not how it's supposed to work.
This is unbelievable! I just tried this on another computer, same OS same version of Code::Blocks and G++.
I am trying to compile two programs using the same header file and definitions. makefile part to make this work.
================================
My headerfile looks like this:
#ifdef ONE
void hello(int s);
#else
[Code]....
How can I include the flag -DONE in my makefile so that
it includes void hello(int s); for "one" and
int pin;
int verification(char* name);
for "two"
Here is my code
#include<msp430.h>
#include<stdio.h>
#include "contiki.h"
#include "isr_compat.h"
#include "string.h"
char dest[20]; //Global Variable
void uart0_send_data() {
[Code] ....
This code is used to transmit and receive the data. My only concern as of now is to create a header file for uart0_init() function.