C++ :: Errors With Using Templates - Unable To Match Function Definition To Existing Declaration
Apr 13, 2013
I've written the following code and keep getting the errors:
Error1error C2244: 'Supermarket<temp>::operator =' : unable to match function definition to an existing declaration
Error2error C2244: 'Supermarket<temp>::setName' : unable to match function definition to an existing declaration
Error3error C2244: 'Supermarket<temp>::setArea' : unable to match function definition to an existing declaration
#ifndef SUPERMARKET_H
#define SUPERMARKET_H
#include<string>
#include<iostream>
using namespace std;
[Code] .....
I moved the files to the .h file, and now I'm getting
Basically I have a text file called words. I'm supposed to extract a word randomly from the file and have the user guess the word according to the definition.
I'm having trouble matching the definition to the word from the text file.
using namespace std; int main(){ int number; int count = 0; string word;
[Code] ....
Here is my text file apple#the usually round, red or yellow, edible fruit of a small tree boat#a vessel for transport by water horse#a solid-hoofed plant-eating domesticated mammal with a flowing mane and tail, used for riding television#a system for transmitting visual images and sound that are reproduced on screens soup#a liquid dish, typically made by boiling meat, fish, or vegetables, etc. bottle#a container, typically made of glass or plastic and with a narrow neck barber#a person who cuts hair toast#sliced bread browned on both sides by exposure to radiant heat radar#a system for detecting the presence, direction, distance, and speed of aircraft, ships, and other objects red#of a color at the end of the spectrum next to orange and opposite violet
I read that Memory is allocated during definition of a variable and not during declaration. Declaration is something like,
Code: int x;
And definition is assigning some value to it. This is what my professor taught. My doubt is if memory is not allocated during declaration, then how the compiler successfully compiles and runs the following, which i had already tried.
Code: #include<stdio.h> #include<conio.h> int main() { int c; int *p=&c; printf("%x",p); getch(); return 0; }
The variable c is only declared. But the program outputs a memory address. Shouldn't it show an error?
Code: #include<stdio.h> extern int v = 0; // Declaration and definition of an external int main(void)
[code]...
Is there any error? Why I take a warning: 'v' initialized and declared 'extern'|||=== Build finished: 0 errors, 1 warnings ===| ???
and what is the meaning of :An extern declaration that initializes a variable serves as a definition of the variable. This rule prevents multiple extern declarations from initializing a variable in different ways.
I changed the name of my Invoice class to 'Application' and then it generated errors such as follows
Error9'Invoice.Invoice' does not contain a definition for 'Documents' and no extension method 'Documents' accepting a first argument of type 'Invoice.Invoice' could be found (are you missing a using directive or an assembly reference?)c:userskeildocumentsvisual studio 2013projectsinvoiceinvoicewritefile.cs1840Invoice
Error3'Invoice.Invoice' does not contain a definition for 'Run'C:UsersKeilDocumentsVisual Studio 2013ProjectsInvoiceInvoiceProgram.cs1921Invoice
I have added my classes here, lso I have added the sln to this post.
using System; using System.Collections.Generic; using System.ComponentModel;
I've included <cstddef> into a project of mine in favour of <stddef.h>. When I tried to compile my project, I get 50+ errors stating that types such as "::size_t", "::div_t" and "::abort( )" have not been declared even though <cstddef> includes <stddef.h>.
I've tried searching both the global namespace and the standard namespace, but neither way works. At this moment in time, I don't have any compiler options enabled that may affect the way identifiers are defined, C++11 isn't enabled (which doesn't affect the <cstddef> header anyway), the project is a C++ project, and I've tried using the plain old <stddef.h> header, but the problems still persist.
I'm using GNU's C++ compiler ("__GNUG__" is defined).
In a .h file there is a function that takes in this parameter:
void (^callback)(float * arg)=NULL
as in a function definition:
void func(void (^callback)(float * arg)=NULL);
What I am able to read is that it takes a function pointer and if not defined it overrides with NULL. The part I do not get is the ^ in (^callback). I only know ^ as a bitwise XOR operator. It also generates issues in my VS2012 compiler (something with CLR). So I would really like to rewrite this part to something else, without the bitwise operator...
The basics of the program is that:It will ask the user whether they want to: Pop, Push , Peek or Exit the program.
When it comes to the Exit case: how do so( tried exit(1) & exit(0) using the internet hasn't brought me much luck either. I am getting these two errors also:
"Error LNK2019 : Unresolved external symbol "int_cdcel peek(void)" (?peek@@YAHXZ)"
Each applying to the functions below.
"Error LNK1120: 3 Unresolved Externals"
I'm not sure their is much more I can say about the problem.
Code:
#include "stdafx.h"#include <stdio.h> /* Libary Collection.*/ #define MAX 10 /* Define: The max size of what we are working with.*/ int push (void); int pop(void); int peek (void);
[code]...
I was also told that I could us if statements instead but, that still will remove the first errors
I have an array of char representing pixels in a bitmap, which I want to modify. I don't think I can just iterate over the array and pass chars into a function individually, because the function needs to take into account the neighboring pixels, too.
I thought of two ways to do this. The first would be to pass the array to the function as an argument, then have the function change it and return it. The trouble is I'm not exactly sure what happens internally when you pass an array to a function and return it. Is it the same array, modified? Or is it a copy of the array, so now you're using twice as much memory?
Alternatively I guess I could have a function with a void return type and pass a pointer to the array. I'm somewhat new to this, but the way I understand it is that a pointer is like the address of a house, while the array is the actual house. So if I give the function the address, it can go to that address and rearrange the furniture inside the house. Then, after the function returns, I can go to that address myself and see all the rearranged furniture, even though the function has already returned.
Is there a problem with the second way? It seems a bit neater, but maybe I'm understanding pointers wrong.
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'm new to C++ i came across this bubblesort program earlier relating to class templates i was wondering how to make this into simple function templates
#include<iostream> #include<iomanip.h> #include<conio.h> #include<stdio.h> using namespace std; template <class t> class bubble
template <class T> void Arreglo<T> :: Registro (ifstream& Entrada) { Entrada >> Cantidad; Dealer = new T [Cantidad]; for (int i = 0; i < Cantidad; i++) {
[Code] .....
It says the following error when I comile it:
error: expected type-specifier before 'Detail' (*(Dealer + i)).Modelo = new Detail[(*(Dealer + i)).AmountModels]; error: expected ';' before 'Detail'
Why will i use explicit instantiation of a template, for a type? If I do not use explicit instantiation, the template is used to create the necessary function then what is the use of explicit instantiation?
In the above eg. explicit instantiation is done for char type. What is the use of this?? If the compiler can make use of the template to make a fn for char type.
I have observed that inline functions can not be prototyped. example:
.cpp file:
inline void whatever() { cout<< "this is inline"<< endl; }
.h file, prototype inline void whatever(); //would ask for a definition
Because of this, I have have just made functions that are used in only 1 .cpp file (ever) inlined, to make it more efficient (and it has demonstrated that it is more efficient). It's worked out fine so far, but what about the scope of the definition??
Since an inline function is like a templated function, in that it can't be prototyped, how are name conflicts resolved, and what is the best practice for writing inline functions??
Example of a conflict:
//in some arbitrary header... void do_somthing(); //in .cpp file that inlcudes the header... inline void do_somthing() { cout<< "I'm doing somthing!!"<< endl; } int main() { do_somthing(); //which one?? it compiles fine though!! return 0; }
I'm looking for a way to enter an unlimited amount of types in the <> part of a template function, I found Variadic templates but I'm not sure if it can do it, all the examples I've found are similar to the C argument list and don't use the <> part of the template at all.
Code: class VAR_EXPORT VAR { public: }; VAR_EXPORT QDataStream &operator>>(QDataStream &p_stream, QSharedPointer<Data>& p_data)
[Code] ....
Above compile and build ok. But when i build another library that use the above, i was shown with all errors complaining operator << and >> definition of dllimport function not allowed
error C2491: 'operator >>' : definition of dllimport function not allowed error C2491: 'operator <<' : definition of dllimport function not allowed
