I understand that the files using the exported class or function need to call this class or function with dllimport and the file containing the exported class or function needs to call this class or function with dllexport. But I tried to use __declspec(dllexport) only instead of the statements above. It still works. Is there anything I am missing?Why'd we have to switch between dllexport and dllimport?
I'm trying to build the gtkmm library using MSVC. One of its source files declares a struct called BuiltinStockID together with some objects of that type - e.g.
Code: // In the header file:- namespace Gtk { struct BuiltinStockID { const char* id;
[Code] ....
GTKMM_API is obviously _declspec(dllimport) (or export) as appropriate. It seems a bit unusual to use extern in addition GTKMM_API but the code won't compile if I try to exclude it. The actual instantiations are in one of the library's source files- e.g.
Code: // In a source file const Gtk::BuiltinStockID APPLY = { GTK_STOCK_APPLY }; const Gtk::BuiltinStockID CANCEL = { GTK_STOCK_CANCEL }; const Gtk::BuiltinStockID OK = { GTK_STOCK_OK };
GTK_STOCK_APPLY etc are simple strings such as "gtk-apply". They mostly refer to image files for the library to load (in this case, for dialog button images) although that's probably not relevant to the problem.
If I run dumpbin /EXPORTS on the built DLL it does seem to have some exported symbols with the names Gtk::Stock::APPLY, Gtk::Stock::CANCEL, Gtk::Stock::OK etc. However, if I write this in one of my own source files:-
Code: Gtk::BuiltinStockID MyStockID; MyStockID = Gtk::Stock::CANCEL; // <--- debugger reports <Bad Ptr> You can see that the Gtk::Stock::CANCEL object is invalid (my debugger reports it as a bad pointer). Likewise, if I try to pass Gtk::Stock::CANCEL as a parameter to a function.
I am writing a program which is using SDL library. I have two different classes which one of them is Timer Class and the other is EventHandling Class.
I need to use some member functions and variables of Timer in some Eventhandling Class member functions, Although I want to define an object of Timer in int main {} and relate it to its member function that has been used in Eventhandling member function in order that it becomes easier to handle it, I mean that I want to have for example two objects of timer and two objects of Eventhandling class for two different users.
I do not know how to relate an object of a class from int main{} to its member function which is being used in another class member function.
I mount a function (parameter - numeric vector; returns a string). However, this same function is used in several classes. To avoid that I keep duplicating the same code within these classes there is a way to do that as the code below?
std::string func( const vector<int> vec ) { //processamento return result; } class A {
C++ Create a Triangle class that has the following member variables: side1 - a double side2 - a double side 3 - a double perimeter area
The class should have the following member functions:
- default constructor that sets the value of all 3 sides of a triangle to 0.0
- a constructor with arguments that accepts values for the three sides of a triangle (member variables) as arguments
- setDimensions - a function that allows the value of the three sides to be entered by the user through the keyboard
- testSides - a function that determines if the 3 values entered can actually be the sides of a triangle. If they do not create a triangle, print the values entered and an appropriate message --The sum of any two side lengths of a triangle must always be greater than the length of the third side: so side 1 + side 2 > side 3 and side 1 + side 3 > side 2 and side 2 + side 3 > side 1 ( all three must be true for the 3 values to make a triangle)
- getSide1 - a function that returns the value of side 1, getSide2 - a function that returns the value of side 2, getSide3 - a function that returns the value of side 3
- getArea - a function that returns the area of a triangle: The formula for the area of a triangle (when the height is not known) is: A = sqrt (p(p-side1)(p-side2)(p-side3)) where p = (side1+side2+side3)/2
- getPerimeter - a function that returns the perimeter of a triangle: Perimeter = side1 + side2+ Side 3
- A displayTriangleInfo function that displays side1, side2, side3, area, and perimeter for a triangle object.
After testing your code for a single object, create an array of 5 triangles. Use a for loop and the setDimensions function to allow the user to set the values for the 3 sides of a triangle, test the vales entered to determine if the 3 create a triangle. If they do create a triangle than use the getArea and getPerimeter functions to calculate the Area and Perimeter for the triangle and use the displayTriangleInfo function to display all of the data for that triangle. If the three values do not create a triangle then print the 3 numbers entered and an appropriate message. In either case the loop should then move on and get the data for the next triangle from the user.
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 keep getting an error saying ui.h:30: error: 'class BTree<Word>' has no member named 'prntInOrder' I have no line 30 in my ui.h but if i count the lines from the .cpp as if they were attached to the .h i find the call to the BTree printInOrder()
here is my ui.h
Code: #pragma once #include "btree.h" #include <fstream> #include <iostream> using namespace std;
[Code].....
As you can see the printInOrder() function is there so would it not see it?
Error:
Code: ui.h: In member function 'void UI::go(std::string)': ui.h:30: error: 'class BTree<Word>' has no member named 'printInOrder'
I have a class having static member.I have get and set methods which will Get and Set Values to this variable. In a multithreaded application does it have any thread safety issues.
Class a { static int b; void Set (int c); int Get(); };
I have a class I am building called date and I've built all my functions to run and done all the necessary error checking in each function. However, my last and final function I have to write is where the # of days passed in as a parameter and then I have to increment the days by that many. And if the user does not increment any days at all in the parameter and leaves it blank, then it automatically increments by one day. I am having trouble with this. So for example if the user was to do this:
Date d1(10, 31, 1998); // Oct 31, 1998 Date d2(6, 29, 1950);// June 29, 1950
d1.Increment(); // d1 is now Nov 1, 1998 d2.Increment(5);// d2 is now July 4, 1950
The function starts out looking like this
void Date::Increment(int numDays = 1) { }
I know I have to use a for loop to accomplish this. I just don't know how to get it to where the days passed in will go to the next month and then days passed in would go to the next year.
Some background: I have a class, A, with members, B and C and D; I also have an array of A objects; I want to be able to have a function which takes said array and performs a certain calculation on either the B, C, or D members of each of the A objects, depending upon certain circumstances; I want to perform the same calculation regardless of which member is to be used in said calculation, such as always assigning the value 3 or multiplying the member's value by a cofactor of some sort.
My question, therefore, is: how I might do this using only one function be it a template or not?
In C++, how do i call a method member of class A from a class B, using a pointer. By the way Class A and B are of different types.
I read that when a pointer is pointing to member function it can only point member functions within the class. But how can i point to a member function outside the class.?????
I have a simple question about inheritance. Consider the following code:
Code: Class Base { int type; Base(){}; }; Class Derived1 : public Base
[Code] ....
I get the following error: Class "Base" has no member "Function1";
That makes sense - as Base has not declared Function1. But how can I loop through a vector of Bases, and then if the object is of type Derived1, call the function Function1?
I'm currently programming a server which uses multiple threads- I have a class for one map in the game. Each map has a thread for timed events(tile regeneration, NPC regeneration, etc.), and a thread for handling NPCs(movement, combat, etc.). A basic structure of the class looks like this:
class Region { public: /* game values are here, they are public so they can be accessed from outside of the class inside of packet-handling functions and such */ int value; void *Function();
[Code] ....
The program crashes when I use a member of the same class the function is located in- in the context I have shown about it would crash on "value++".
I am supposed to implement the member functions of class Person.
class Person { public: Person(); Person(string pname, int page); void get_name() const; void get_age() const;
[Code] ....
The code I wrote is below. Where I am struggling is the program does not allow me to input age. Therefore, I cannot test if my temp for age works. It automatically defaults to 0 because it hasn't taken input. Here is my code:
// Program Title: Person function // Program Description: The program prompts the user for first and last name and age. // It then prints the output that was provided by the user.
#include<iostream> #include<string> using namespace std; class Person {
We're assigned a project working with classes and fractions. My goal is to display a fraction in proper from based on 2 arguments passed to a class member function proper();
My strategy was to utilize the greatest common factor between the 2 arguements, then divide both the numerator and denominator by that number and then it would display.
The program actually runs, but only seems to divide the numerator and not the denominator. This in return makes my other class member functions have incorrect comparisons and sums.
Code: #include<iostream> #include<conio.h> class Fraction { friend void compare(Fraction a, Fraction b); friend void sum(Fraction a, Fraction b);
I get the following error in XCode whenever I try to access the member I created 'randomGen' in a separate class in a different header file. I have made sure to include the header file and have tried to access it through an object.
This is the code I enter when trying to access the method from randomiser.h in main.cpp. It is also an overloaded function with doubles and integers:
RandomG randomiser; randomiser.randomGen(); // 'Call to member function 'randomGen' is ambiguous'
This is the code inside randomiser.h:
#include <string> #include <iostream> using std::string; using std::cout; using std::endl; class RandomG {
[Code] ....
This is the error inside xcode: [URL] ....
I have tried seperating the code for the functions in another class (main.cpp) and then running and it seems to works, so I'm not sure why I can't put everything in the .h file and then access it?
I would like it in a seperate file so it doesn't clutter my main. I am writing a game with SDL so that might be confusing and I would like the window to have a random title and other random properties, so it would be easier to use a function.
