C :: Calling Function Via Function Pointer Inside Structure Pointer
Mar 14, 2013
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.
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.
error: request for member 'character' in '* ptr', which is of non-class type 'datastructure*' error: request for member 'character' in '* ptr', which is of non-class type 'datastructure*'
These errors are related to " *ptr->character='a'; printf("Ptr: %c",*ptr->character); "
I want to access "character" data inside the structure "trial" by a pointer to pointer "ptr" inside function "function",but I couldn't find a way to do this.
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?
This works if the function pointer being passed to the event manager is not a member function.
I have two other classes Scene and Object that could potentially use this EventManager to create callback events. Scene and Object are both pure virtual objects. How can I pass a pointer to a member function of the child classes of both Scene and Object? I am fine with just having two separate watchEvent functions for Scene and Object but how do I pass the type of the Object or the type of the Scene? The child classes are unknown as they are being created by someone using this game engine.
For example, if I want to make a player object it would be something like
class PlayerObject : public Object{...};
Now that PlayerObject type has to find its way to PlayerObject::functionToCall(). I think I need templates to do this but, since I never used them before
This is how I intend to use this
class OtherScene : public Scene{ void p_pressed(void){ //pause }
Code: const MenuData breakfast[NUMOFBREAKFASTITEMS] = { {"Egg Breakfast", "Two eggs with a side of bacon and two slices of toast.", "", "2 Eggs, 2 Toats, 2 Bacons", "", 250.00}, {"Pancake Breakfast", "Three Buttermilk pancakes served with butter and syrup.", "", "Three Pancakes, Butter, Syrup", "", 200.00},
[Code]....
What I'm trying to do is call the printReceipt function in the main, but I'm doing it wrong. Here is my attempt.
im tasked with creating a linear search script using functions on a 10 element array. the elements are to be supplied by the user as is the search target.
I understand how to create the array and gather that information from the user as well as howto set a variable for "target", this is what im calling it. Those two parts are simple enough.
I am not fully understanding the calling of an array in a function as a pointer. i semi understand the use of a pointer and howto call a normal pointer in a function. i also understand that an array is nothing more then a "special" pointer with a set of consecutive address blocks for the size of the array.
My first user defined function is simple enough
Code: ReadArray(int A[], int size){ int i; printf("Please enter %d integer numbers separated by spaces: ", size); for (i = 0; i < size; i++) scanf("%d", &A[i]); }
Sso nothing out of the ordinary there. that should be a standard for loop and use of scanf, sadly prof has not covered ssanf or any of the other options so i am stuck using scanf for now. maybe someday down the line in a other program or after this course ill get the chance to learn about better options for gathering data from the user.
I am confused as to my next function:
Code: void SearchArray(int A[], int target, int size);
I've not written any code here yet as im not sure if i should call the A[], or *A for the first type of the function?
If i call *A do i then use something like this for my search:
Code: for (*A = 0; *A < size; *A++) if (*A < target) or use A[] insteadA?
Code: for (i = 0; i < size; i++) if (A[i] = target)
int example (int [], int, *int,*int,*int,*int); int main () { My code will be here example (int array[], int size, &a,&b,&c,&d); // Like this??? I try it didnt work
I was wondering what magic does a * pointer before function actually do? Today our programming teacher asked us to look into it and explain it in the next class!
#include<iostream> using namespace std; int *binary(int []);
As the title says, i'm using a function which returns a pointer to a struct:
the struct is the following:
Code: typedef struct POINT { uint16_t x; uint16_t y; }
Coordinate; the function i'm using:
Code: Coordinate * Read_XTP2046(void) {static Coordinate screen; //calculations to determine the coordinates screen.x=(temp[1]+temp[2])/2; screen.y=(temp[0]+temp[2])/2; // and so on... return &screen;}
The question is: how do i catch this pointer and make it into a Coordinate struct in which i can read the x and y.
In my main program i would do the following:
Code: Coordinate cor; cor = Read_XTP2046();
This does not work, as the function returns a pointer, but how to transform this pointer into a Coordinate struct.
I would like to initialize an arry containing function pointers with adresses of functions that have a variable number of arguments.
Below the code that works in principle. I would however get rid of the warning message during compilation pointing to the initialzation of the funtion pointers in the array. How do I need to cast the pointers to the functions ?
Code: gcc func_ptr_init.c func_ptr_init.c:28: warning: initialization from incompatible pointer type func_ptr_init.c:32: warning: initialization from incompatible pointer type
I am trying to return a pointer from a method. Below is a sample of my code.
CSubnode * CTest::GetSubNode() { return m_psubnode;//this is declared in CTest as CSunbnode * m_psubnode } //in another class m_subnode = m_ptest->GetSubNode(); //m_subnode is declared as a pointer
I declared a pointer in main with value 0, so I want to change its value so that it points to other variable from a function, I guess the function creates a copy of my pointer that's why whatever I do within function doesn't change the real direction of the pointer in main. I've been trying something like this:
#include <stdio.h> void redirectionate(char *str, char *ptrCopy); int main() {
How this code work bcoz when pointer variable assigned in called function and how different values get as resultant output, ans 2 97 for below code. How the code wil execute so that i can validate ans
#include <stdio.h> int main() { int i = 97, *p = &i; foo(&i); printf("%d ", *p);
I am trying to use "remove_if" with a predicate function inside a class. The code intends to remove the grid cells which an agent cannot move into (from among all possible cells).
That code would work if it was not in a class and the predicate was not a member function. However, now I receive long error messages which I guess refer to incompatibility of remove_if template with the predicate parameter (one error includes : error C2064: term does not evaluate to a function taking 1 arguments).
