I'm trying to pass a class object by reference.
total = mathfunction(i);
}
double mathfunction(retirement& j)
{
double R = 0.00, m = 0.00, r = 0.00, t = 0.00, totaled = 0.00,
numerator = 0.00, denom = 0.00, temp = 0.00;
[Code]....
I only tried to pass by reference because I figured passing by value would be a larger pain in the neck.
I am having trouble working with third party dll's, libs and header files. I am trying to call a function.here is the function that is suppose to be called.
bool COAuthSDK::GetRequestToken(CClientDetails &objClientDetails)
it has this info of what it needs :
Name IN/OUT Description
m_environment IN Optional. Possible values are SANDBOX (default) and LIVE.
m_strConsumerKey IN OAuth consumer key provided by E*TRADE
m_strConsumerSecret IN OAuth consumer secret provided by E*TRADE
m_strToken OUT Returned by the function if successful
m_strTokenSecret OUT Returned by the function if successful
m_strCallback IN Optional; default value is "oob"
here is the COAuthSDK header
#ifndef _OAUTHSDK_H_INCLUDED_
#define _OAUTHSDK_H_INCLUDED_
#include "ETCOMMONCommonDefs.h"
#include "ETCOMMONOAuthHelper.h"
using namespace std;
[code].....
when I try to build the function it says that its in the dll's so I know I have to call it.here is the link to the build site if needed URL....
I'm trying to pass an reference of the object ifstream to my constructor as such:
// myClass.cpp
int main(){
ifstream file;
myClass classobj = myClass(file);}
I am defining the constructor as follows, in myClass.cpp:
myClass::myClass(ifstream &file){
// do stuff
}
I get the error of "No overloaded function of myClass::myClass matches the specified type."
Also, when I build the program, it tells me "syntax error: identifier 'ifstream'"
Also, I made sure I included this:
#include <iostream>
#include <fstream>
#include <sstream>
What am I doing wrong? How can I pass an ifstream reference to my constructor?
class A (abstract)
class B : A
class C {
void add ( A(&*?) a )
std::vector<std::unique_ptr<A>> data; //unique_ptr<A> because A is abstract and therefore vector<A> isn't possible
}
upper situation. What is the best way to pass add an object of class B to C?
with C::add(A* a){ vector.push_back( unique_ptr<A>(a) ); }
and
int main() {
C c;
c.add( new B() );
}
This works, but i don't think it's very nice, because you could delete the pointer in main. What happens then with the unique_ptr? I could probably make C::add( std::unique_ptr<A> u_p ); but maybe it can be avoided that the "user" (in main() ) has to create the unique_ptr itself.
i want to store reference to a const object in my class as a member variable, as follow:
I basically want a readonly reference to |Data| in Device object.
Code:
class Device {
Device(const QList<QSharedPointer<Data>> & dataList) : _listRef(dataList) {
} protected:
const QList<QSharedPointer<Data>> & _listRef;
}
This does not allow me to initialize _listRef as something like NULL when it is not applicable.Also, i must change all my constructors and its child class to include an initialization of _listRef!!
What is the alternative? Is pointer the nearest? which of the following should be used?
Code:
const QList<QSharedPointer<Data>> * _listRef;
or
const QList<QSharedPointer<Data>> *const _listRef;
or
const QSharedPointer<QList<QSharedPointer<Data>>> _listRef; ????
I've been given an assignment with the below questions.
1. What is the difference between pass by reference & pass by pointers?
2. What is the use of the initialization list in the constructor?
3. What is meant by a reference & its advantage?
4. Class has a reference, pointer and a const. Is it possible to write the copy constructor & assignment operator overloading funciton? how? ( Since reference is there, I'm not sure on how to write for it)
5. Example for a variable decleration and definition? (I know for function but for variable don kw how)
6. static and const static what is the difference??
// explain difference between pass by value and pass by reference
void addOne(int i)
{
i++;
}
void addOne(int& i)
{
i++;
}
i think i understand both concept. i know that pass by value is that the function receiving those values makes actually a copy of those parameters. Passing by reference makes the variable in the main function to actually see those changes in the other function, instead of a copy, and apply them to the variable in the main function. my question is, why would i pass it by reference if i just can make a return type function.
View 5 Replies View RelatedI need to put my Dice() function as pass by reference and something as a pass by value, it can be in the same function.
#include <iostream>
#include <ctime>
#include <cstdlib>
using namespace std;
[Code].....
I am trying to use web api in order to return custom json response keys. For this i have return a custom class to return json response
Custom Class:
using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
[Code].....
I have a combobox with Items 1024
2048
4096
8192
String cach = form.comboCache.SelectedItem.ToString();
I am using the above code to retrive an item selected by user,But this line is giving an exception "Null Reference Exception, Object reference not set to an instance of an object"
(Pass-by-Value vs. Pass-by-Reference)
Write a complete C++ program with the two alternate functions specified below, each of which simply triples the variable count defined in main. Then compare and contrast the two approaches. These two functions are
a) function tripleByValue that passes a copy of count by value, triples the copy and returns the new value and
b) function tripleByReference that passes count by reference via a reference parameter and triples the original value of count through its alias (i.e., the reference parameter).
I need to pass an array of 10 instances of a custom class to a function. The snippets of code are posted below. How would I do this right?
The prototype:
Code:
int Search(Vertex vertex[], ofstream &outfile);
The implementation in the main function.
Code:
Search(vertex[10], outfile);
How do you pass 2D arrays by reference??
View 2 Replies View RelatedI built a program that finds the average amount of days missed per employee. I am now attempting to modify my program to pass values by reference rather than passing by value. I created 3 functions: int numOfEmployees(); int numOfDays(int); double avgDays(int, int);
in the prototype I use the ampersand sign int numOfDays(int&);
in the actual function I use numOfDays(int& employees)
I am just not able to get the call to the function to work the program will crash when I modify it with the ampersand signs.This is the original code I am trying to modify:
#include <iostream>
using namespace std;
int numOfEmployees(); //Prototype for numOfEmployees
int numOfDays(int); //Prototype for numOfDays
double avgDays(int, int); //Prototype for avgDays
[code]....
//program to form a header file
/* using pass by reference in pointer */
#include <iostream>
#include<math.h>
[Code].....
I've written some code that I am currently threading but I am unsure how to pass by reference, or rather why my pass by reference is failing.
I am passing an array of floats by reference, this works fine when not threaded but I am given the error that float*&field does not match std::reference_wrapper<float*>.
Anyways. Here's the code.
The method:
diffuse(int b, float*& field, float*& pField, float diffFactor, float dt, int iteration)
The thread:
std::thread diffuseThread(diffuse, 1, std::ref(u), std::ref(prevU), visc, dt, iteration);
I built a program that finds the average amount of days missed per employee. I am now attempting to modify my program to pass values by reference rather than passing by value. I created 3 functions:
int numOfEmployees(); int numOfDays(int); double avgDays(int, int);
in the prototype I use the ampersand sign int numOfDays(int&);
in the actual function I use numOfDays(int& employees)
I am just not able to get the call to the function to work the program will crash when I modify it with the ampersand signs. I know I have to re-work my program, but I am having a hard time understanding how.
This is the original code I am trying to modify:
#include <iostream>
using namespace std;
int numOfEmployees(); //Prototype for numOfEmployees
int numOfDays(int); //Prototype for numOfDays
double avgDays(int, int); //Prototype for avgDays
[Code]......
What is the difference in pass by pointer and pass by reference? As per my understanding, there is no difference much.If a function accepts pointer, then NULL check can be performed.other than this i'm not able to see any big difference..
View 3 Replies View RelatedI cant get my insert function to insert to the head of the list I dont think I'm passing the pointers correctly.
#include <iostream>
using namespace std ;
struct list1 {
int data ;
list1 * next = NULL;
[Code] .....
I have a struct which has an array inside of it:
struct someStruct{
int structArray[999];}
Now when I want to access that array, I have the following:
ptrSomeStruct->structArray[someIndex];
But now I want to pass structArray to this function by reference so that it can adjust the array as needed and I can continue to use the array back in my caller function:
void adjustArray(void *& someArray){}
How do I accomplish this?
I just want to know if there is any real difference between the two below, if yes, when would i use one over the other? I would thought the "&" is pointless in below function, as far as the data is concerned.., the only things is with "&", if the pointer address value is changed in Test function, it will affect the caller's copy of data. Both function should behave the same if data is changed.
Code:
Between
void Test(QSharedPointer<Data> data)
{
}
and
void Test(QSharedPointer<Data> & data)
{
}
I am using session to pass object from controller to custom class in MVC Web API. here is my code, i am getting error at session.
public HttpResponseMessage Get()
{
var person = db.Persons.ToList();
[Code]....
In Visual Studio 2010 C++
I have a series of existing text objects
The text properties names are
item1_lbl,
item2_lbl,
item3_lbl,
….
Based on a selection I want to change an object. I generate the name of the object I want to change in a string so from this string is there a way to get a pointer to the correct text object that is same name?
Due to the nature of this requirement, I've made a very minimal example, which would adequately solve my issue, without resorting to use of pointers or copy constructors.
Basically I'm trying to pass an object as a reference to the template function, rather than a copy as it's seeing. I'm needing to do this without editing Obj::Call to accommodate a reference as its first parameter, as it'd break other calls.
You'll notice in the following code the object will be destroyed upon passing, while the object defined is still in-scope due to the infinite end loop.
#include <iostream>
#include <string>
using namespace std;
class Obj {
public:
string name;
[Code] ....
In the past I tried ref(), which appeared to stop this happening, however it created a blank copy of the object instead.
I don't understand how my code not run.
#include "stdafx.h"
#include<iostream>
using namespace std;
struct student{
char name[30];
char birthday[20];
char homeness[50];
float math;
[Code] ....