C++ :: Pass By Reference To A Template Function Through Parameter Only

Sep 19, 2014

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.

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C++ :: How To Pass Function Pointer As A Template Parameter

Jun 13, 2013

void extf(int a) { }
template<typename P>
struct A {
// 1
template< void (*F)(P) >
static void call(P arg) {

[Code]...

Why it is not working? What would be a proper way to pass function pointer as a template parameter?

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C++ :: Template Function Parameter Passing By Reference Instead Of Copy / Pointer

Sep 19, 2014

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;
Obj(string name): name(name) {cout << "create " << this << endl;}

[code]....

In the past I tried ref(), which appeared to stop this happening, however it created a blank copy of the object instead.

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C++ :: Array Into Function As Parameter Pass

May 2, 2013

I have been working on this all day, and its due in like an hour and a half. I have done everything the program wants except the last part. Here is the assignment:

Write a program that inputs 10 integers from the console into an array, and removes the duplicate array elements and prints the array. You may assume that all the integers are between 0 and 100, Write at least 1 function in addition to the main function, and pass an array into that function as a parameter. e.g.

Please enter your 10 numbers: 1 2 3 4 5 6 7 8 9 10
The array contains: 1 2 3 4 5 6 7 8 9 10

Please enter your 10 numbers: 1 1 3 3 3 6 7 8 9 9
The array contains: 1 3 6 7 8 9

Please enter your 10 numbers: 1 1 1 1 1 1 1 1 1 1
The array contains: 1

The bolded part is what I cant get to work. I have tried this and it keeps telling me I have not identified the items when I have.

Here is my code:

#include "stdafx.h"
#include <iostream>
using namespace std;

[Code]....

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C++ :: How To Pass A Void Function As Parameter

Oct 20, 2013

How can I pass a function as a parameter? I have a class that I'm trying to reuse and one of the methods in this class need to take three parameters, two ints and a function. In other words I want to be able to call a custom function every time this method is invoked when used in other classes. The function I want to call will not return any values, its a void function.

In my Class:

void Utility::someFunction(int var1, int var2, void customFunction) {
int num1 = var1;
int num2 = var2;

[Code] .....

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C :: Declare A Struct Then Pass It As A Parameter Into Function

Dec 8, 2014

I have some code here where I try to declare a struct then pass it as a parameter into a function to do something to it:

Code:
struct _user {
char * initial[3];
int pos;
} user;
int initial_add (struct user * initial_list, int initials, char * buffer) {

[Code] ...

I get the error :
server2.c:15: warning: "struct user" declared inside parameter list
server2.c:15: warning: its scope is only this definition or declaration, which is probably not what you want

[Code] ....

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C++ :: Passing A Function Parameter By Reference?

Sep 25, 2012

I created the following code to pass the the variable 'inputVoltage' by reference to the function 'input'. It certainly works when I run the program, but I dont think it is a standard way of doing it, i.e. the use of '*' and '&' is not according to convention ? Or perhaps the way did it is acceptable ?

int input (double *inputVoltage);
int main ( {
double inputVoltage;
input(&inputVoltage);

[Code]....

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C++ :: How To Pass Constant BYTE Array Declared In Function As Parameter

Apr 20, 2013

I have this code:

const BYTE original[2][4] = {
{0x00, 0x00, 0x00, 0x00},
{0xFF, 0xFF, 0xFF, 0xFF}
};
void function(const BYTE** values){

[Code] ....

You might notice that the above code doesn't compile, this is the error:

cannot convert parameter 2 from 'BYTE [2][4]' to 'BYTE *'
1>
Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast

Even after some search I couldn't really find an answer to my problem, how do I pass the const BYTE array which I declared above in the function as a parameter (or what structure do I need to set for the function as a parameter)?

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C++ :: Passing A Function As Template Parameter

Dec 26, 2013

Pseudocode:
template<typename T /*, some parameter for member_function */>
class Foo {
public:
void someFunction() {
T t;
t.member_fuction(...);
} }

I'm trying to make the call to T::member_function a templated value because member_function might vary by name in my scenario. Since std::mem_fn isn't a 'type', i can't do something like Foo<std::string, std::mem_fn(&std::string::clear)> foo;

I also want to take into account that member_function might have more than one parameter. That is, the first parameter will always be something known but there might be other defaulted parameters.

The only thing I can think of is to make a proxy structure, something like this:

template<typename T, T> struct proxy;
template<typename T, typename R, typename... Args, R (T::*member_function)(Args...)>
struct proxy<R (T::*)(Args...), member_function> {
R operator()(T &obj, Args.. args) {
return (obj.*member_function)(std::forward<Args>(args)...);
} }

Which would then allow me to do (for example) this:

Foo<std::string, proxy<void(std::string::*)(), &std::string::clear> >

when Foo is implemented like this:

template<typename T, typename member_function>
class Foo {
public:
void someFunction() {
T t;
member_function()(t);
} };

That implementation works for me.

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C++ :: Pointer - Pass Reference Variable Into Function

Oct 4, 2013

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] ....

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C/C++ :: Two Array Member Pass As Parameter - Expression Syntax Error For Function

Nov 8, 2013

In my project, GreedyKnap::calKnap(int nItem, int nCapacity, float fWeights, float fProfits);

This function include two array member pass as parameter. how can i do this?

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C/C++ :: Get Return Type Of Function In Template Parameter

Jul 27, 2012

Is this really the preferred way to get the return type, for use in a derived class, of a function defined in the template parameter?

template<class PARAMETER> class C {
         protected:
            typedef typeof (reinterpret_cast<PARAMETER*>(0))->function() returntype;
      };  

This works just fine for me, but seems inelegant.

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C/C++ :: Const Pointer Pass By Reference In Print Function

Apr 21, 2014

I am trying use a print function to print out data in a struct. My questions are:

1. I have to use pass by reference. For the print function, I am passing the struct pointer as a reference, however, I don't want the print function to accidentally change anything. How can I make it use const to ensure that?

2. The deleteprt function doesn't look right to me. I feel like it should just be delete ptr not delete [] ptr.

#include <iostream>
#include <fstream>
#include <iomanip>
#include <cstdlib>
#include <string>
using namespace std;
struct Inventory {

[Code] .....

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C++ :: How To Create A Function That Takes A File Object As A Reference Parameter

Feb 21, 2013

I have a school project in which need to create a function that takes a File Object as a Reference Parameter. Supposedly, it should allow me to read the first piece of data from others separated by a space from a file. The later be able to continue reading from the next piece of data.

I know how to set things up to read from the data file, such as using

Code:

#include <iostream> , and

Code:

ifstream inputFileName;
inputFile.open ("nameOfFile");

I also understand how to pass a variable by reference to a function. But I simply cannot put the two items together!

I tried using

Code:

void getFileInput (ifstream &); //parameter
getFileInput ("nameOfFile") // call
void getFileInput (ifstream &dataFileName)

In the function I used

Code:

ifstream inputFile;
inputFile.open (dataFileName);

I'm just not getting an understanding of this concept!

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Visual C++ :: Dice Game - Creating Pass By Value Function Reference

Nov 27, 2014

i have a project where i create a dice game, the user rolls 2 dice and the computer roles 2 dice. the player that wins 3 out of 5 rolls wins the game. I have completed the requirements, but i wanted to create a pass by value function for "void Dice()", I'm not too sure how that works?

Code:

#include <iostream>
#include <ctime>
#include <cstdlib>
using namespace std;
//creating my variables and their values
int compinput;

[Code] .....

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C++ :: Undefined Reference To Template Function

Oct 21, 2013

I am coding a RTS game but I cant compile my dataLoader function. It gives that errors when want to call it:

//Window size
int width;
int height;
if( !dataLoader<int>( width, "settings/resolution.txt", "width" ) || !dataLoader<int>( height, "settings/resolution.txt", "height" ) )

[Code] ....

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C++ :: What Is The Difference Between Pass By Reference And Pass By Pointers

Jan 23, 2013

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??

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C++ :: Template With A Specialized Template Class Parameter?

Nov 2, 2014

how I want the code to look. Only problem is it doesn't work (Line 11). I have some experience with templates but I'm not a pro.

Basically I want the "Channels<3>" to be a type that I can use to specify a Cable with similar to vector<float/int> it would be Cable<Channels<2 or 3>>.

What have I messed up with the syntax?

#include <iostream>
#include <vector>
using namespace std;

[Code].....

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C++ :: Difference Between Pass By Value And Pass By Reference?

Jul 2, 2014

// explain difference between pass by value and pass by reference

void addOne(int i)
{
i++;
}
void addOne(int& i)
{
i++;
}

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C++ :: How To Pass Integer Parameter To Main

Feb 6, 2015

//This program demonstrates a function with three parameters

#include <iostream>
using namespace std;
//function prototype
void showSum(int, int, int);

int main(int x) { //Take notice int x parameter
int value1, value2, value3;

[Code] ....

I ran the program from command prompt:

C:WindowsSystem32>"E:CS Ia.exe"
Enter three integers and I will display their sum: 0
0
0
0

Also, btw, x = 1
C:WindowsSystem32>echo %ERRORLEVEL% // return value (normally 0)
124234

[Code] .....

My problem is I do not understand what is going on when I try to pass an argument to the program. (Since it is defined int main(int x)).

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Visual C++ :: Pass Parameter In Dialog Box

Feb 12, 2014

I need to pass a variable to a dialog box.

Code:
Doc* pDoc;
Dialog dlg;
int input = dlg.DoModal();

When I call dlg.DoModal() I need to somehow pass the pDoc into the dialog box. Everything I need the variable for is taking place inside the oninitdialog function. Is there anyway to pass the variable to that function?

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C++ :: Pass By Value And Pass By Reference?

Apr 17, 2013

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.

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C/C++ :: Pass By Reference And Pass By Value?

Nov 27, 2014

I 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].....

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C/C++ :: Pass A String As A Parameter And Use It To Open A File?

Feb 21, 2014

why I'm getting an error with this code? I'm trying to pass a string as a parameter and use it to open a file:

class txt{
private:
string tempstring;
vector<string> strings;
char filename[10]; //not using this right now

[code]....

but I get this error:

[Note] no known conversion for argument 1 from 'const string {aka const std::basic_string<char>}' to 'const char*'

I thought strings were just const character arrays

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Visual C++ :: Pass More Parameter In Overriding New Operator

Jul 24, 2014

[URL]

class CMyclass
{
public:
CMyClass(BOOL bUseWhichMemManager);
void* operator new(size_t);
void operator delete(void*);
};

I create two memory manager called CMemManager1 and CMemMangaer2, using different algorithms to allocate buffer. Now I want to control which memory manager to be used, when calling new.

I try to add a parameter bUseWhichMemManager to the constructor, but in overrided new function, there are no way to access the parameter. Is there a way to pass more parameters to new operator, such as:

void* operator new(size_t size, BOOL bUseWhichManager);

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C++ :: Pass By Value And Reference

Nov 25, 2013

(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).

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