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;
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:
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.
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 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.
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'm having some problems in understanding how the code below works and why it produces the output it produces.. What I'd expect is that both functions, namely `add_1' and `add_2', would print the same output; but I've been proven wrong :/ So why does the second one get different memory addresses for the same variable?
Code should be self-explaining:
Code: template<typename... Types> void add_1(Types&&... values) { // by the way: why do i have to use `const int' instead of `int'? std::vector<std::reference_wrapper<const int>> vector{ std::forward<Types>(values)...}; std::cout << "add_1:" << std::endl; for (const auto& value:vector) { std::cout << &value.get() << std::endl;
How do I prevent user passing a class or a structure or aanoter function to my function print. I mean i know if a wrong thing is passed that i'll get an error eventually but is there a way to explicitly check what has been passed. How is this done usually ?
I am trying to wright a program that takes student grade data from a command line file, calculates a final grade, and copies the final grades to an output file. So far I have two functions, one that creates a student structure by allocating memory for it and returning its address, and one that should take that address and fill it with data from a line from the input file. My ultimate goal is to use a linked list to connect all the structs, but for now I just want to get the functions working. When I run what I have so far, I get an error C2440 (using visual 2010) that says "cannot convert from 'cStudent *', to 'cStudent', and points to the line where I call my fill function. How should structure pointers be passed?
Is there such thing as passing a winforms label by reference? For example, can I create a pointer label and pass the address to a function? I've looked online but couldn't find anything. Perhaps that's a sign?
The function should pass the square of the first input parameter and the cube of the second input parameter back to the calling routine. I thought I could use a recursion but its not going to work.
I am getting a few compile errors for what might be a simple thing to do. I am opening a file in main, passing that pointer to a function and checking the contents of that file with a regex before I pass it on to build a BST. I am getting the following compile errors, what is wrong. Here are the errors:
Code: gcc main.c fileCheck.c -o tree main.c: In function `fileCheck': main.c:19: error: syntax error before "FILE" fileCheck.c: In function `fileCheck':
[Code] .....
Fatal error: Command failed for target `tree' Here is the two files and header that seem to be causing me the problems.
main.c
Code: #include "main.h" //#include "node.h" int main(int argc, char *argv[]) FILE *fp; if (argc > 2)
I am working on a project and decided to try something simple before I start adding items. I am calling a function from main and that function has a file pointer.
Here is my main.cpp
Code: #include <cstdio> #include <string> #include <iostream> #include "main.h" extern FILE *fp; using namespace std; int main(int argc, char *argv[])
My test file consists of several characters and digits. Nothing special and I at this point in time do not have any type of formatting that needs to be adhered to. I am simply wanting to read the file character by character and print it out. When I run the program, I get this symbol:
Code: If I use a printf statement, such as: Code: printf("%s ", nextChar);
And then have another template function declaration for all the attractor functions where I pass the same template value as in the first one.
As you can see, I'm calling another functions inside called attractors(_tmp). I know that one way around it could be to get rid of that function and just do all the logic inside of each if statement. Is there any way to pass the same template function parameter within a template function parameter?
But when I try to build it, I get this error on line 24:could not convert template argument 'lambda' to 'void (*)(const string&) {aka void (*)(const std::basic_string<char>&)}'|
I thought the lambda expression I wrote would decay to a function pointer matching the template parameter. I can guess that the constexpr qualifier might have changed the type, but without it my compiler complains that lambda needs to be declared as constexpr...
So is there a way to pass lambda expressions as template parameters?
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 ?
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.
function fun recieves the address(which is NULL) and then allocates the memory for the Box; Let's say I cannot return the address of new allocated p and I can't also use that pointer p(from main) without passing it into a function.
Q: How can I make it that I could operate in function "fun" as I operate on orginal pointer p(from main), right now I'm just passing the address to my function but I can't change the 'global' pointer p ;(.
I remember in pascal it's like: "function(var pointer:[pointer to sth])" and all is done.
I'm trying to call a function via a function pointer, and this function pointer is inside a structure. The structure is being referenced via a structure pointer.
Code:
position = hash->(*funcHash)(idNmbr);
The function will return an int, which is what position is a type of. When I compile this code,
I get the error: error: expected identifier before ( token.
Is my syntax wrong? I'm not sure what would be throwing this error.
what I am trying to do is to pass to a function the address of an array of structs, so I can later modify the items within the struct, within the array
Code: typedef struct { //A struct of name auctionint bidder;float bid;} auction; void myFunction (auction * auctionItem[]){(*aucItem[x]).bid = y;(*aucItem[x]).bidder = z;} int main(){auction theItems[10]; myFunction(theItems);} Where x, y, and z can be any number.
When I try to run my code the IDE (I'm using Code::Blocks 12.11) does not give me any errors, but it does give me a warning:
warning: passing argument 3 of '<function name>' from incompatible pointer type [enabled by default]
and the note:
note: expected 'struct <struct name> **' but argument is of type 'struct <struct name> *'.Also, when I run the program, it will crash and return garbage.