I wrote out this coding to deal with template functions, but how would I invoke the function and to display the statements which im trying to invoke?
#include <cstdlib>
#include <iostream>
using namespace std;
#include <string>
[Code].....
I'm trying to implement a simple template array class, but when i came into the operator< i actually have to use a template :
my code is something like :
template<typename _Type, std::size_t _Size>
class array {
public :
[Code] ......
but i am having an error of shadows template param 'class _Type' is it w/ the name conflict between the array template parameter and the function template parameter ?
I have a function:
template<class Iterator, class T>
void a(Iterator, Iterator, const T&);
and I want to be able to simplify calls to 'a' with calls like
a(someIteratableContainer);
instead of having to call:
a(someIteratableContainer.begin(), someIteratableContainer.end(), valueOfTheContainersElementType);
I also want to be able to generalize the function to handle any of the standard iteratable contains: array, vector, deque, whatever.
I was under the impression I could write:
template<template<class T> class U> a(U<T>& container) {
a(container.begin(), container.end(), g(T()));
}
where 'g()' returns an object of the element type. However, the compiler is claiming, no matter how I write a call to the overload, the original template is selected and/or the overload is invalid, depending on the various ways I attempt to write said overload.
I'm using MS' optimizing compiler CL 13.10 (one from VCToolkit 2003) along with WinAPI threading functions and is being compiled as a C console program.
I was wondering how to implement threading in a production setting? I've seen and tried various examples, but they all show basically the same thing - startup in main, run their function, clean up, and then the program exits.
I don't know the proper terminology, but I was looking for two maybe three functions to run simultaneously with a loop in main. I tried a small test program and was wondering if it's setup correctly.
A structure is used as the argument for each function.
int running = 1; // global variable
DWORD WINAPI function_1(LPVOID);
DWORD WINAPI function_2(LPVOID);
main() {
HANDLE hndThreads[2];
DWORD threadIDs[2];
[code].....
Right now, function_2 is just a copy of function_1's definition. Everything *appears* to do what I want, but is it setup correctly?
I use g++ compiler and need some tips on how to get started with making a c++ GUI. The project I have will need a gui that will allow the user to conveniently invoke executable (the command-line args they take are long and inconvenient to enter manually) and basically print their output streams into a control (e.g. read only textbox). There will be a few graphics involved too (the input for those graphics will be from a file), so I'll need a library that will allow drawLine methods (nothing too fancy, I don't need a gaming library).
Making a GUI in c++. In Java the ability to make a GUI is a part of the native library, so the c++ way seems foreign to me.
I am trying to build a web application that uses p/invoke to access a method. Similiar to the one used here - [URL] However I keep getting the following error message - Unable to load DLL 'MyDll.dll': The specified module could not be found. (Exception from HRESULT: 0x8007007E) I read say to change the output directory to match that of the Mydll directory I have tried that and it still does not work.
View 6 Replies View RelatedI am having problems invoking methods in a nested class using reflection. I have the following:
A parent class, Group, that holds instances of a simple class called Signal. I want to modify the number of instances inside the group class often. So, all my code has to be dynamic and use reflection to know how many instances of signal there are inside the Group class.
class Group{
public static Signal name1 { get; set; }
public static Signal name2 { get; set; }
public static Signal name3 { get; set; }
[Code]....
I had no luck invoking the method of the instances of signal class that are inside the Group class. I tried getting the methods name using getMethods() but could not navigate through the syntax.
How could I invoke and pass parameters to the method of the instances of signal using reflection? Is there a better way of accessing the properties and methods of nested classes?
I want to override the operator new in a class, as follows:
class CMyclass
{
public:
void* operator new(size_t);
void operator delete(void*);
[Code]....
However, in debug version, whenever MemoryManager.Alloc(size) returns NULL, which means alloation fails, the AfxThrowMemoryException will cause the following exception:
Access violation reading location 0x#######
I have main thread that creates an WebBrowser2 COM object. and i want to invoke JScript functions on it from another thread. i try to use GIT but still doesn't work for me.. there is a problem with marshal WebBrowser2 for JScript?
View 4 Replies View Relatedi want to use a class to print data stored as vector or array with different data types. i also want the print function two take more than one vector or array or combination of both so that they can be written to file as two columns. so i wrote the following class:
right now it has only one member function for printing two vectors. later i'll add additional functions as required.
note: there has to be template functions inside the class
i also want the object to be global so that i need not pass it as an argument to other calling functions
class printdata
{
public:
template<typename T1,typename T2>
void SaveData( vector<T1> &data1,vector<T2> &data2, std::string var)
{
[Code]....
then i want to call this template function in another ordinary function written in a seperate cpp file
these function declarations are put in a header file. so i need know whether i should put the declaration of the template function in the header to use the function in different functions
i want to use a class to print data stored as vector or array with different data types.
i also want the print function two take more than one vector or array or combination of both so that they can be written to file as two columns.so i wrote the following class:
right now it has only one member function for printing two vectors. later i'll add additional functions as required.
note: there has to be template functions inside the class / i also want the object to be global so that i need not pass it as an argument to other calling functions
class printdata {
public:
template<typename T1,typename T2>
void SaveData( vector<T1> &data1,vector<T2> &data2, std::string var){
std::ofstream myfile;
std::string filename;
[code].....
then i want to call this template function in another ordinary function written in a seperate cpp file these function declarations are put in a header file. so i need know whether i should put the declaration of the template function in the header to use the function in different functions.
I have this:
string input;
unsigned short choice;
...
istringstream valid(input);
...
if(!(valid >> choice))
{
//some error
}
Ok. My code is almost 1000 lines, and I have splited some functions in headers. But the same function doesn't work:
template <typename T> bool valid_input(const string& input, T var)
{
istringstream valid(input);
return (valid >> var);
}
You can check it here: [URL] The output is correct, but in my machine with C++11, MinGW 4.8 (64 bit in a 64bit-Windows8), the output is incorrect. Why?
If you want more specific info, the problem is that I use input, I think. I use std::getline(std::cin, some_string).
I am assigned this program by my instructor and he wants me to convert the function to function template. I do not know how to do that. How to get good grades in final.
#include <iostream>
#include <sstream>
#include <fstream>
using namespace std;
#include "Test.h"
struct char_list {
char head;
[Code] .....
I have this class templates And This UML.I have to write this function +operator=(source: Array<ElemType, SIZE>): Array<ElemType, SIZE> but I do not know how to start the declaration / or start the function. I have to return a template but I do not know how to do it,
UML
Array<ElemType, SIZE>
-elements: ElemType[SIZE]
+Array()
+Array(source: Array<ElemType, SIZE>)
+operator=(source: Array<ElemType, SIZE>): Array<ElemType, SIZE>
+operator==(other: Array<ElemType, SIZE>): Boolean
+operator!=(other: Array<ElemType, SIZE>): Boolean
<<L-value>>+operator[](index: Integer): ElemType
<<R-value>>+operator[](index: Integer): ElemType
[code]....
I want to use a template function of a class.
This is my code:
#include "Comparison.h"
#include <iostream>
using namespace std;
int main(int argc, char** argv) {
Comparison c;
[Code] ....
But I get the error message:
main.cpp:10: undefined reference to `int Comparison::max<int>(int, int)'
I'm trying to create a callback wrapper for pointers to member functions of any class by using templates, std::function and std::bind. This will be used to send incoming sf::Event's to classes who register callbacks with an event manager. I based my code off of the example on this page: URL.....Here's what I have:
class EventCallback
{
std::function<bool(const sf::Event&)> func;
public:
template<typename T>
EventCallback(T* object, bool(T::*func)(const sf::Event&)) { func = std::bind(func, object, std::placeholders::_1); }
bool run(const sf::Event& evt) { return func(evt); }
};
[code]....
I am a beginner, got confused about:
template<typename T> int compare(T &a,T &b);
int compare(const char *a,const char *b);
char ch_arr1[6]="world",ch_arr2[6]="hello";
compare(ch_arr1,ch_arr2);
After running the code above,we got to know the non-template function is called. What I know is that the array arguments ch_arr1,ch_arr2 will not be converted to char * because the parameters are references in the template functions.
ch_arr1,ch_arr2 need to be converted to const char * if compare(const char *a,const char *b) were called.
I just wanna know what exactly happened behind that? and why?
I understand template functions and how to call them explicitly when no arguments are passed to them but can't seem to instantiate them explicitly when it resides within a class or struct.
struct Creator {
template <class T>
T * New(T * p) {
return new T;
}
};
Creator cr;
MyClass * pMy = cr.New<MyClass>(); //gives compile error
The compiler complains about MyClass (or any other) being used illegally in expression ...
I was just wondering how is this generally resolved. Let say you have this large function that runs in two modes. In the first mode it evaluates the data passed to a function as a map the the second mode it fills the map. example:
Code:
template <typename Map, typename Int>
void func(Map & map, Int i){
int z = 0;
string zz;
[Code] ....
The point is i do not want to write a large function just to include different modes so i decided to set "i" to be a mode identifier. However when i want to compile my function given two modes i get an error since the modes are not recognized (obviously). if i pass map as
Code: map<int,int>
and mode 1 i get an error here :
Code: map[z] = z; besause map
Code: map[z] expects z to be an int not string and the other way around (though in practice this cannot happen since i set the modes). So am i restricted to writing my function for both modes separately (polimorf.) or there is a way to make my example work.
I want to have a template function that is a member of a class. Is this possible? This code snippet is how I would think the syntax would go, although it doesn't compile. How would I achieve the same effect?
Code:
class myclass {
public:
int member ;
} ;
template <typename T> void myclass::func( T& arg )
[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].....
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.
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] ....
Firstly, is it legal to overload a template function in a class? This is what I did
class FILE_txt
{
public:
FILE_txt(const char* );
[Code]....
I try to create small project in order to better understand how key word static works with templates . However some compiles errors crush my plan.
1>------ Build started: Project: 4.2b - Ex 1. Static Variable for Array Def Size. Templates, Configuration: Release Win32 ------
1> main.cpp
1>c:all myс++ha level 6solution level 6solution level 64.2b - ex1. static variable for array def size. templatesarray.cpp(40): error C2724: 'Array<Type>:efaultSize' : 'static' should not be used on member functions defined at file scope
[Code] .....
Consider the following code:
Code:
template<class TYPE>
void MultiplyByTwo(TYPE data) {
cout <<"Double = " << data * 2 << endl;
}
If I declared that code in a header file I'd be able to call it with an int, float, double or whatever. But where does the actual code get instantiated? Is it effectively inlined?
What I'm wondering is if there'd ever be any scenario for putting such code in a DLL - e.g.
Code:
#ifdef BUILDING_MY_DLL
#define MY_DLL_API __declspec(dllexport)
#else
#define MY_DLL_API __declspec(dllimport)
#endif
template<class TYPE>
MY_DLL_API void MultiplyByTwo(TYPE data) {
cout <<"Double = " << data * 2 << endl;
}
I just tried it and was slightly surprised to find it wouldn't compile. It compiles fine when actually building the DLL but when I try to build something else which uses that DLL I get compiler error C2491 (definition of dllimport function not allowed).
I guess that kinda makes sense if template functions are effectively inlined... or is there some other explanation....