C/C++ :: Function Pointers From External Class?
Jun 8, 2014How can i use a function pointer from external class? Say we have a class tuna
Tuna:
int foo(){
return 45;
}
int (*foobar)();
[Code].....
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C++ :: Creating Public And Static Field In A Class - Unresolved External Symbol Error
Apr 5, 2014I'm trying to create a public and static field in a class called ResourceManager. But when trying to access the field even from inside the class it wont work. I'm getting this error message:
Error 1 error LNK2001: unresolved external symbol "public: static int ResourceManager::num" (?num@ResourceManager@@2HA)
Here's my code:
ResourceManager.h
Code:
class ResourceManager {
public:
static int num;
static void loadContent();
[Code] .....
I'm using Visual Studio 2012.
C++ :: Inline Function Prefix - External Call And GCC?
Jan 17, 2014I have some functions inlined using the inline function prefix. If the function is called from outside the file (so a seperate psp-gcc -O3 ... filename.c filename.o compile command, when only the function is changed), will the other files be updated too? (I'm using the pspsdk toolchain).
Example:
max.c
inline byte max(byte a, byte b) {
return a>b?a:b;
} use1.c
void use1() {
if (max(1,2)==0)
[Code] ....
If I compile this, next change the max function and recompile using make (the compiler only takes the changed max.c->max.o file, next links them together) will use1.c&use2.c be updated with the new max.c function?
C++ :: Creating Array Of Pointers To Base Class To Point To Derived Class Objects Dynamically
Jan 16, 2013Please consider the following code :
#include <iostream>
using namespace std;
class superclass;
class subclass1;
class subclass2;
[Code] ....
As you can see I want to create a dynamically allocated storage of references to a parent class each of which can then point to a child class, how ever I do not know how to extract the child class out again from that array so i may access its variable b.
C++ :: Class To Manage Pointers Better - Some Errors
Nov 19, 2013I wrote a class to manage pointers better (because I am making a large program and don't want to call a constructor on somthing that was already deleted... etc...), but I am getting some compiler errors. I'm not sure what to do.
here is the class prototype:
template<typename type>
class pointer_class{
public:
pointer_class() : dat(NULL), del(false) {}
explicit pointer_class(const pointer_class<type>& d) : dat(NULL),
[Code].....
C++ :: Vector Of Pointers - Abstract Class
May 13, 2014I need to create a vector of pointers and hold the book objects in it. then i have a virtual function in my books which is a pure virtual in LibraryItems. When i try to add the books object in my code, i understand that since the scope runs out there is no object that is added. so when i run print it gives me an error.
#include<iostream>
#include "books.h"
#include "library.h"
#include <vector>
using namespace std;
int main(int argc, char * argv[]) {
vector<LibraryItems* >libraryInfo;
[Code] .....
C++ :: Class With Pointers And Dynamic Arrays
Apr 25, 2014Class with Pointers and Dynamic Arrays
View 2 Replies View RelatedC++ :: How To Hold Pointers / References To Abstract Class
Nov 15, 2014I have an abstract class named Terrain, and a class named RoadMap, which supposed to hold an N*N array of Terrains. But I'm not sure what type should the RoadMap class hold:
Code:
#ifndef TERRAIN_H
#define TERRAIN_H
class Terrain {
[Code] ....
I can't use an array of refernces here, so I tried this:
Code: Terrain** terrain; and then I thought this was the way to go:
Code: Terrain (*terrain)[]; But now I'm not sure.
The N*N matrix size supposed to be determined according to a given input... What type should I use there?
C++ :: Member Function In Derived Class Call Same Function From Its Base Class?
Sep 18, 2013How can a member function in my derived class call the same function from its base class?
View 1 Replies View RelatedC++ :: Hold Vector Of Pointers In Same Class As Instances Of Those Objects?
Feb 10, 2015Using SFML, I had a Board class which held multiple vectors of all of my object types in the game, and then it also held a vector of pointers to the memory addresses of these object instances, like this
class Board{
//...
std::vector<AbstractObject*> GetAllLevelObjects(){ return allLevelObjects; }
//so these are used to hold my object instances for each level
[Code]....
When looping through this vector and drawing the sprites of the objects, I get the runtime error 0xC0000005: Access violation reading location 0x00277000. I solved this error by storing the vector of pointers in the class that holds my Board instance, but I'm wondering why only this solution worked? Why couldn't I just have my vector of pointers in the same class that the instances of those objects were in?
C++ :: What Are Function Pointers
May 21, 2012What are Function pointers , what are the benefits of using it?
View 4 Replies View RelatedC :: Passing Pointers Into Function?
Dec 3, 2013I want to scan numbers in from within a function, but have access to them in main, so I tried using pointers to do so:
Code:
// Path Of Exile socket colours simulation
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
[Code].....
C :: Size Of Function And Pointers
Apr 6, 2014I have this simple program:
Code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
static unsigned char cmd[]={
0x01,0x80,0x00,0x00,0x00
[Code] .....
All is right except the size. Why does it give 80x1 as size instead of the digit 5?
C :: Pointers For A Prime Function?
Oct 15, 2013i'm trying to determine if a number from a file is a prime number using pointers first I wrote a function that determines if the number is a multiple of 7, 11, or 13. Then i wrote a function to see if the number is odd or even. Are they correct? Later i will print the results on screen but i'm extremely confused with pointers and i'm not sure how to write this prime function...
Code:
void divisible(int *n, int *result) {
if (*n % 7 == 0 || n % 13 == 0 || n % 13 == 0) {
*result = 1;
[Code] .....
C :: Point Of Function Pointers
Sep 27, 2014I'm wondering about the point of pointers to functions. When is it used?I saw the below example. It doesn't make sense to me. I mean we can easily write code that does the same without having to use pointers.
Code:
#include <stdio.h>
int addInt(int a, int b); // Adds 2 integers
int add5to4(int (*function_pointer)(int, int));
int main(void)
{
int sum;
int (*function_pointer)(int, int);
}
[code]....
C/C++ :: How To Use Pointers To Arrays In Function
Feb 25, 2015I am trying to use pointers to arrays in my function.
I can get the pointers to work outside of a function but I just can't figure out how to make them work in my function.jwhittle58, on 25 February 2015 - 06:06 PM, said:
I am trying to use pointers to arrays in my function. I can get the pointers to work outside of a function but I just can't figure out how to make them work in my function.
C/C++ :: Typedef Function Pointers
Apr 21, 2014I'm given a mathematical function F(x) = etc..., the user inputs an initial x point and a final x point. The program finds the integration.
Below is a snippet of code.
/*Typedefs as given by prof*/
typedef double (*mainFunction) (double);
typedef double (*calcArea) (mainFunction, double, double);
int main () {
answer = calcIntegral(mainFunction *curve1, calcArea *calcAreaRect, a, B)/>; /*it doesn't like this line*/
printf("The integral from %lf to %lf is: %.4lf", &a,&b,&answer);
return 0;
}
curve1 is a function that accepts a double and returns a double, calcAreaRect takes mainFunction main(which is F(x) so i stored the fn in curve1), double and double.
C :: Static Array Of Function Pointers
Jan 29, 2015I basically have some code that lets users register callbacks into a callback table at a specified index. There is one element in this table for each event that can trigger a callback. I basically do something like this:
In a header file
Code:
typedef struct _GMclient
{
GMcommunicator gcomm;
GMclient_callback callback_table[(int)MAX_CALLBACKS];
}GMclient;
typedef int (*GMclient_callback)(GMclient*, void*, void*);
Then I allow them to set the callback with a function that basically ends up doing this (in a .c file that includes the previous mentioned .h file):
Code:
void
GMclient_register_callback(GMclient *client,
GMclient_callback fxn,
int index)
[Code] ....
Then later when I need to invoke that callback, I pull it out of the table
Code: GMclient_callback *fxn = client->callback_table[CMD_INDEX];
However, I get compilation errors:
Code: src/gmanager_client.c:43:6:
error: a label can only be part of a statement and a declaration is not a statement...
C :: Program To Use Void Pointers In A Function
May 14, 2014As part of my ongoing c programming education, I have written a program to use void pointers in a function,
Code:
#include <stdio.h>
#define MAX_NUMBERS 10
size_t size(void *object);
int main(void) {
}
[code]....
Now I think that the result 4 is the size of the pointer, so I'm confussed as why it doesn't give me the same result as 40.
C :: How To Pass 2 Array Pointers To A Function
Aug 4, 2013How would I pass let say 2 array pointers to a function X , allocate memory for them in X , fill them with values and get them back in my main function without creating a structure.
example:
Code:
void X(int *a, int*b){
a= malloc ...
b = malloc ...
// fill a and b
return them back to the main function
}
void main(){
[Code]...
C++ :: Using Pointers Instead Of Reference Variables In Function
Mar 26, 2013The following function uses reference variables as parameters. Rewrite the function so it uses pointers instead of reference variables, and then demonstrate the function in a complete program.
int doSomething(int &x, int &y)
{
int temp =x;
x = y * 10;
y = temp * 10;
return x + y;
}
I understand how to covert the reference variables to pointers, however I am stuck on this error. Either I get the error listed in the title or (with a few changes) the error "invalid conversion from 'int' to 'int*'"
What am I doing incorrectly?
#include <iostream>
using namespace std;
int doSomething(int*, int*);
int main(){
int X, Y, result;
[Code] ....
I have multiplied both x and y by 10 and then added them together!
Here is the result " //I really didn't know how else to use the "doSomething" function in a meaningful way. So... I just stated what the function does.
<< result << ".
";
system("PAUSE");
return 0;
}
int doSomthing(int *x, int *y)
[Code] .....
C++ :: Function Pointers Inside Array
Apr 6, 2014Ive recently got into function pointers, i find that they can be quite handy for making your program very 'dynamic'.
However, the syntax is very confusing for what i want to do
This is what i want to do
I want to hold function pointers inside an array, but this array is dynamically allocated ( malloc, realloc, etc )
This is the current syntax ive come up with, but i dont think it is correct
void ( **drawFunc ) ( void*, SDL_Surface* );
C++ :: Hash Table Of Function Pointers?
Dec 15, 2014Is it possible to create a hash table of function pointers so that functions can be referenced by their name (using a string?)
View 2 Replies View RelatedC++ :: Function Passed By Pointers Or Reference?
Sep 28, 2014I am going to read some codes about image processing and I need to understand functions like this one below?
BOOL Trans_Geo_Affine(CImage *pImgSrc, CImage *pImgDst, BOOL bMatrix,
BOOL bHvInversed, double fScale_xx, double fFlex_xy, double fSkew_yx,
double fRotate_yy, double fTx, double fTy, int nInterpolation, BOOL bResize, BYTE cFill)
[URL]
two parameters, CImage *pImgSrc and CImage *pImgDst. I think they are class pointers and the function is passed by reference. What should I learn to understand this function and its parameters? How should I use this function? how to use the function with two parameters CImage *pImgSrc and CImage *pImgDst.
C++ :: Function Pointers Versus Subclasses
Feb 25, 2013I am in a position to choose between function pointers and subclassed objects. To make it clear, say I have to notify some object of some action (a timer for example); refer to the following two choices (a very basic code for demo purposes):
Version 1
typedef void TimerCallback(void *args);
class Timer{
public:
Timer();
[Code] .....
Version 2:
class TimerTask{
public:
TimerTask();
virtual ~TimerTask();
void timedout()=0;
[Code] .....
which one is the standard C++ way and which one is efficient?
C++ :: Passing Pointers By Reference To Function?
Mar 4, 2013If f1 and f2 are two user defined functions.
main(){
int *p;
f1(&p)
}
f1(**p){
f2(&p);//
If I've to pass the pointer by reference again in another function, will I've to do something like this?
}
f2(***p){
**p = NULL;
}