shared pointers


 
Thread Tools Search this Thread
Top Forums UNIX for Advanced & Expert Users shared pointers
# 1  
Old 03-22-2009
shared pointers

I am new to shared pointer conceot in C++ and hence require some clarification:

For example:

class A
{
public:
virtual ~A()
{
}
int x;
};
typedef boost::shared_ptr<A> APtr;


APtr getA()
{
return APtr(new A());
}
A::A()
{
x = 0;
}

When ever I call APtr getA() will every instance of object A will see x as 0?
# 2  
Old 03-22-2009
I would like to modify and clarify my point here

I have a class in which constructor I have declared a member variable as 0. Now I am using a shared pointer to access object created in heap. So incase if we create another instance of the class will there only be one instance of the class but two shared pointers or two instances of class.

My interest is the class constructor is initializing the member variable to 0. Now before the second instance is created that member variable is incremented. So when the second call is made will the first instance see the value of x as 0?

Please confirm
Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. Programming

Pointers and array

Hello, I read from a book exercise for a challenge. How to print out each letter of char array a by two different pointers pa and ppa in the example? I have tried my code for letter "r" by testing without full understanding as only the first one worked. #include<stdio.h> int main() { char... (17 Replies)
Discussion started by: yifangt
17 Replies

2. Programming

Shared library with acces to shared memory.

Hello. I am new to this forum and I would like to ask for advice about low level POSIX programming. I have to implement a POSIX compliant C shared library. A file will have some variables and the shared library will have some functions which need those variables. There is one special... (5 Replies)
Discussion started by: iamjag
5 Replies

3. Programming

Pointer to pointers

Hi guys, I'm trying to understand pointers in C and made a simple example and I've problems with It. Can someone help? #include <stdio.h> #include <stdlib.h> #include <assert.h> int f1(char **str_); int main(int argc, char **argv) { char *str = NULL; f1(&str); ... (3 Replies)
Discussion started by: pharaoh
3 Replies

4. Programming

Need help with the Pointers in C

I have a special character called ô. When it is declared as a character variable its showing it can be printed. But when it is declared as a character pointer variable its showing it cannot be printed. I am just wondering why its happening like this.. c1 = '@'; c2 = 'ô'; char *fp; fp="XXô"; if... (1 Reply)
Discussion started by: sivakumar.rj
1 Replies

5. Programming

Shared memory for shared library

I am writing a shared library in Linux (but compatible with other UNIXes) and I want to allow multiple instances to share a piece of memory -- 1 byte is enough. What's the "best" way to do this? I want to optimize for speed and portability. Obviously, I'll have to worry about mutual exclusion. (0 Replies)
Discussion started by: otheus
0 Replies

6. Programming

restricted pointers

Hi all. I am trying to use restricted pointers to allow the gcc compiler optimize the code, but I have not been able to make it work so far. I am testing with this code: #include <stdlib.h> #include <stdio.h> #include <time.h> #include <sys/time.h> void vecmult(int n, int * restrict a, int... (0 Replies)
Discussion started by: carl.alv
0 Replies

7. Programming

pointers

Hi I mash with pointers in C. I solve this problem about 5 hours and I don't know how I should continue. void InsertFirst (tList *L, int val) { tElemPtr new; if((new = malloc(sizeof(tElemPtr))) == NULL) Error(); new->data = val; new->ptr = L->frst; L->frst = new;... (2 Replies)
Discussion started by: Milla
2 Replies

8. Programming

Shared memory in shared library

I need to create a shared library to access an in memory DB. The DB is not huge, but big enough to make it cumbersome to carry around in every single process using the shared library. Luckily, it is pretty static information, so I don't need to worry much about synchronizing the data between... (12 Replies)
Discussion started by: DreamWarrior
12 Replies

9. Programming

pointers

is this a valid c declaration int (*ptr(int *b)); plz explain... (4 Replies)
Discussion started by: areef4u
4 Replies

10. Programming

Pointers and array

hi all, let say i have a pointer exit, and this exit will store some value. how can i store the value that the pointer points to into an array and then print them out from the array. thanks in advance (2 Replies)
Discussion started by: dianazheng
2 Replies
Login or Register to Ask a Question