I want to have a function pointer inside a typedef struct but I get a segmentation fault when I run my code. Here's my code:
#include <stdio.h>
typedef struct Foo {
void (*bar)(int);
} Foo;
void func(int x) {
printf("display: %d
[Code] ....
Can typedef and struct be put inside a class like below?
Code:
class classA {
private:
typedef void(classA::*aFnPtr_t) (); //pointer-to-member function
struct strctA {
int a;
int b[100];
};
typedef struct strctA strctA_t;
typedef void (classA::*bFnPtr_t)(strctA_t*); //pointer-to-member function
...
}
"
#include <stdio.h>
struct datastructure {
char character;
};
void function(struct datastructure** ptr);
[Code] ....
These codes give these errors:
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 need to create the following brain damaging abomination:
I need a function pointer type to a function that has an argument of the same function pointer type and returns the same function pointer type.
The purpose is to enable a type of subroutine threading scheme for a small application specific scripting language. The question could just as well have been posted to the C forum.
This syntax works, but Payload is a generic type which I can coerce into the right pointer type via a cast. This is ugly IMHO. I could also hide it as a pointer in the FlipState class since I've forward declared this.
But this is an extra indirection in a performance critical part of the code, and also ugly.
Code:
class FlipState ;
typedef PayLoad (*FuncPtr) (FlipState *fs, PayLoad P) ; This syntax blows chunks using gcc on the other hand. Code: class FlipState ;
typedef FuncPtr (*FuncPtr) (FlipState *fs, FuncPtr P) ;
[Code] .....
This is hardly surprising. The compiler could not possibly understand what I was defining in the typedef. I think what I need is some kind of way to forward declare a function pointer type and then redefine it properly.
Is such a think even possible or am I just SOL? This one is mind boggling. We know how to do this with classes or other complex data types, but the syntax eludes me for both C++ and C.
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.
I am having problems with passing my values through functions.
Here is my code:
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
void test(int**);
void test2(int**);
[Code]....
i need to return a struct pointer dynamically allocated inside a function call void function() which is done using 'out parameters' in following code
struct my_struct {
int x;
} void my_function( my_struct** result ) {
my_struct* x = new my_struct{ 10 };
//...
*result = x;
}
Now i have a doubt, so if i want to print the return value from struct pointer, should i need to print it in the void function() or in the caller the function...
I'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.
while writing code i got a question. For example i created a class named as unit.
Think a simple game, and the unit class will belong the units.İf i give the preferences as private one by one, it will be irregular. For a detailed game; height, weight, race, hair preferences, eyes... Strength, dexterity, charisma, intelligence, wisdom, constution... experience, damage, armor...
and should i use struct to group them? And how to can i use struct at the inside of class as private?
Looking for info about the typedef 2-dimensional array ....
Suppose I have typedef two_Darr[3][3];
How to declare this and how to pass it to other function definition in the main function ....
This is with Linux gcc
Code:
typedef struct _a
{
int id;
} a;
typedef struct _b
{
a my_a;
my_a.id = 1; // error: expected specifier-qualifier-list before "my_a"
} b;
I get error: expected specifier-qualifier-list before "my_a"
I must set the id for the kind of struct created inside the struct def because main() will be casting based on this id. Thats how I will know which structure b contains by it's id, there could be hundards of different structs with different values I will cast to the correct one and know it's members by it's id. How do I ?
How can I display the elements of an array inside struct something like this
struct ABC {
double a[3];}
void show( const ABC & x );
ABC x{18, 'W', { 1.1, 2.2, 3.3 }};
show(x); would output {18, ‘W’, {1.1, 2.2, 3.3}}
Code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct info info;
[Code] ....
I have a class "Result" with a single template function Set(const std::string& arName, T& val) and a specialization of this function Set<Real>(const std::string& arName, Real& val) where Real is a typedef for double. The class is in a shared library and I use it in my main program. If I do result->Set<GLOBAL::Real>("U", 100.0); the wrong template function is called!
I check this by the output with std::cout.
Maybe it's a problem with the typedef.
If I link the object file of the Result class directly to my main program (no shared library), it works.
typedefs.hpp:
namespace GLOBAL {
typedef double Real;
} results.hpp
#include <iostream>
[Code] ....
Alright, so I have a code that's not giving me errors, but it doesn't seem to retain what I put into an array. Not sure If I'm missing something...
Code:
#include <stdio.h>
int main (void)
{
const char *pointer;
const char alphabet[] = "ABCDEFG";
pointer = &alphabet[5];
printf("pointing to %c of the alphabet
", pointer);
return 0;
}
Trying to get my pointer to return the letter in the [5] spot or "F". Not receiving any errors when compiling, but I seem to get different answers every time I run it.
i had a structure as follows:
struct a{
int x;
struct b{
int y;
b *next;
}b;
};
when i try to access as follows:
struct a *a;
a->b=a->b->next;
i got the following error: base operand of ‘->’ has non-pointer type
How can I add the variable adress to a void pointer inside of a class?
class variant2 {
private:
void *Vvariant=NULL;
public:
template<typename b>
variant & operator = (b *adress)
[Code] ....
if possible i want avoid the '&' when i assign the variable address.(variant2 f=varname;//like you see i don't use the '&')
for the moment i just need put the address to Variant pointer. but i receive several errors .
how can I call and print the Pointer:
ptr->address
Code: #include<stdio.h>
struct account {
int address;
int value;
[code]....
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main() {
struct stock{
char symbol[5];
int quantity;
float price;
[Code] ....
- In the final output
Value
%.2f
- How is the final pointer reference at line33 leading to the output %.2f ? (i do understand that the %% is used to display a %] ....
I am currently trying to printf several values of a struct pointer but with little success.
#include"Header.h"
/*
In header:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <conio.h>
struct FileStruct {
char FileQuestion[64];
[Code] ....
As you can see I am trying to re-crate the output from the first loop in my second loop, however it is with little success. The second loop's first run re-crates the last output of the first loop and if I use FileStructPointer++ or -- the output goes broke.
See attached for how it looks in the console window.
Attached image(s)
This is a c++ Code. I want to read a address to a pointer. When I try to do so it generates an error. I did is >> obj1[0].contentAdress; in main.
struct node3{
node3(){
nextContent = NULL;
for (int i = 0; i<1020; i++)
content[i] = '';
[code]...
no operator found which takes a right-hand operand of type 'node3 *' (or there is no acceptable conversion)
I am trying to store data in a struct to be able to read it latter . have problems initializing this.
struct FoodAndDrink {
struct Food {
char* CannedGoods[2] = {
"Canned Spaghetti",
"Canned Tuna",
[code] .....
i want to use a class to print data stored as vector or array with different data types. i also want the print function two take more than one vector or array or combination of both so that they can be written to file as two columns. so i wrote the following class:
right now it has only one member function for printing two vectors. later i'll add additional functions as required.
note: there has to be template functions inside the class
i also want the object to be global so that i need not pass it as an argument to other calling functions
class printdata
{
public:
template<typename T1,typename T2>
void SaveData( vector<T1> &data1,vector<T2> &data2, std::string var)
{
[Code]....
then i want to call this template function in another ordinary function written in a seperate cpp file
these function declarations are put in a header file. so i need know whether i should put the declaration of the template function in the header to use the function in different functions
i want to use a class to print data stored as vector or array with different data types.
i also want the print function two take more than one vector or array or combination of both so that they can be written to file as two columns.so i wrote the following class:
right now it has only one member function for printing two vectors. later i'll add additional functions as required.
note: there has to be template functions inside the class / i also want the object to be global so that i need not pass it as an argument to other calling functions
class printdata {
public:
template<typename T1,typename T2>
void SaveData( vector<T1> &data1,vector<T2> &data2, std::string var){
std::ofstream myfile;
std::string filename;
[code].....
then i want to call this template function in another ordinary function written in a seperate cpp file these function declarations are put in a header file. so i need know whether i should put the declaration of the template function in the header to use the function in different functions.
I am attempting to implement function pointers and I am having a bit of a problem.
See the code example below; what I want to be able to do is call a function pointer from another pointer.
I'll admit that I may not be explaining this 100% correct but I am trying to implement the code inside the main function below.
class MainObject;
class SecondaryObject;
class SecondaryObject {
public:
[Code]....
I keep on getting error message while trying to pass a function inside a for_each loop.. I have a vector and i used for_each loop to go through the rows in that vector, Now I need a function to do something
Example this is what I am trying to achieve
for_each (label.begin(), label.end(), addToTemporaryVector());
void DataPartitioning::addToTemporaryVector(){
cout<<"sucess";
}
But I get an error message saying: error: invalid use of void expression