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?
Say I have a class that requires dynamic allocation to implement a few of the operators. Take "+" for example; I need to create a new object to hold the sum of the two parameters whose size is not known at compile time.
I'm pretty sure the standard way to indicate a failure inside the overloading function would be to throw an exception. However I am currently involved in an embedded(ish) project where the spec. says no exceptions are to be used.
I think I have 2 options:
1. Return an "invalid" object (with a flag indicating an error has occurred) and check for this after each operation.
a = b + c if (a.err) // handle error or
2. To forsake operator overloading entirely and think up a new way of doing things where all functions that involve dynamic allocation can return error codes. but this seems rather terrible too as I may end up with something like:
objA a if (add(&a, b, c) == -1) // assuming b and c are initialized before this snippet starts // handle error
Is there a number 3 that I haven't thought of? It seems that not allowing exceptions is fairly common even in the non-embedded world [URL] so how is this normally done? or is operator overloading usually avoided when exceptions are not allowed?
but I got two major errors 1: "object f abstract type is not allowed" error.-----why not? 2: "the derived class must implement the inherited pure virtual method"-----Did't I?
I want to overload prefix and postfix increment(++) operators with friend function. I also have to use the constructors for this. How can I do this? in C++
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 ?
Consider the class specification below. Write the prototype (i.e. header) of a member function to overload the insertion operator (i.e. <<). The << operator is to output the data members of an instance of class StudentTestScores into an output stream. Your definition should allow for chaining of output operations (e.g. cout << x << y; where x and y are of type StduentTestScires).
#include <string> using namespace std; class StudentTestScores{ private: string studentName; float *testScores; // used to point to an array of test scores int numTestScores; // number of test scores
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 having some issues with my code. For the produce function i am getting an error saying 'no instance of overload function produce() matches the argument list' and also for the lines buffer[head].data = message; buffer[head].time = current_time i get an error saying 'expression must have pointer to object type.
In the code i'm not sure if i passed the variables to the function correctly. I have attached the code .....
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
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
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.
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.
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,
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;
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.
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 )
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;
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:
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
