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?
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.
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.
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]....
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] .....
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] ....
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)?
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.
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?
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.
I'm making a code that uses a Function pointer. The problem is, when I try to compile appears an error like:
error: no matching function for call to 'rnVector::rnVector()'
Here's part of the code:
phiFunction::phiFunction(double (*f)(rnVector), rnVector (*df)(rnVector)) {
//... Here comes the code stuff...
}
i need to pass myboard.board (board is in the class Cboard and it is an array of int) to a function in a class called piece however this is troubling . i need to pass it as pointer os that i could change its value here under is my code.
main.cpp Code: #include<iostream>
#include"board.h"
#include "pieces.h"
[Code].....
I'm having a problem understanding something with pointers. I was trying to pass a pointer into a function in MSVC-2013, like
char* charptr;
and then calling
myfunct(charptr);
and then inside the function i would set charptr equal to another char ptr, simply like
charptr = anothercharptr;
But this actually caused a compile failure in MSVC, saying charptr is being used without being initialized. in Code::Blocks it just gives buggy output.
I solved this issue by calling the function like
myfunct(&charptr);
and declaring the function like
myfunct(char**);
and then I had to dereference the charptr in the function when assigning it to another ptr, so
*charptr = anothercharptr;
It seems like you should be able to just pass a ptr into a function and change its address to that of another pointer? My main question is really, what is the value of a pointer? I thought the value of a pointer was just the memory address it contains. But then I had to reference it to pass it into the function.
What is the difference between the value of the char* charptr written as either charptr and &charptr?
#include <iostream>
using namespace std;
void myfunc(int* ); // what do i put in these parameters to accept a mem loc of a pointer
int main () {
int x = 5;
[Code] .....
SOLUTION:
#include <iostream>
using namespace std;
//Purpose to create a function that returns a pointer to a pointer
int** myfunc(int**);
int main () {
int x = 5;
[Code] ....
The printArray function should take in the dynamically created array and the size of the array as parameters. It should print out the contents of the array.
#include <iostream>
#include <string>
using namespace std;
[Code].....
My problem is that how to write the code to print the array using pointers. I've been stuck for awhile trying to figure it out.
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] ....
I am trying to create a callback system for input events in my game engine.
Here is a cut down version of the EventManager.h file
#include "Controls.h"
#include "Object.h"
enum MouseEventType{PRESSED, POINTER_AT_POSITION, PRESSED_AT_POSITION };
[Code].....
This works if the function pointer being passed to the event manager is not a member function.
I have two other classes Scene and Object that could potentially use this EventManager to create callback events. Scene and Object are both pure virtual objects. How can I pass a pointer to a member function of the child classes of both Scene and Object? I am fine with just having two separate watchEvent functions for Scene and Object but how do I pass the type of the Object or the type of the Scene? The child classes are unknown as they are being created by someone using this game engine.
For example, if I want to make a player object it would be something like
class PlayerObject : public Object{...};
Now that PlayerObject type has to find its way to PlayerObject::functionToCall(). I think I need templates to do this but, since I never used them before
This is how I intend to use this
class OtherScene : public Scene{
void p_pressed(void){
//pause
}
[Code].....
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] .....
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].....
I'm trying to pass the pointer of a dynamic array into a template function, but it keeps telling me there is no matching function to call because the parameters I'm passing in are wrong. how to make the function accept the pointer.
//main
int main()
{
srand(unsigned(time(NULL)));
int size;
int *list;
int *listCopy;
[code].....
I have in the past written code for templated functions where one function argument can be either a function pointer or a Functor. Works pretty straightforward.
Now I am in a situation where I am actually trying to pass a function pointer as template argument to a class. Unfortunately this does not work, I can pass the Functor class but not the function pointer. Below code illustrates the issue:
Code:
#include <string>
#include <iostream>
#include <sstream>
#include <cstdlib>
// For demonstration
const char * external_library_call() {
return "FFFF";
[Code] .....
The idea is to have the definition of the Record class simple and readable and have a maintainable way to add auto-conversion functions to the class. So the lines I commented out are the desirable way how I want my code to look. Unfortunately I could not come up with any way that was close to readable for solving this.
//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)).
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?
I was having problems changing the value of my head node I passed it as an argument as head which would be the address. The parameter was defined as struct node *head. like this
bool deleteNode(struct node *head, struct node *delptr)
I tried manipultaing pointer values to change head node value but it did not work. I saw some code online which used pointer to pointers(in code below) to change head node value it worked I dont fully understand why. Would like better understanding of why.
Would also like to know why the argument call needed &head instead of just head.
remove = deleteNode(&head,found); opposed to remove = deleteNode(head,found);
#include "stdafx.h"
#include<iostream>
struct node{
[Code].....
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
[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);