Problem using void pointer as a function argument

Posted by Nazgulled on Stack Overflow See other posts from Stack Overflow or by Nazgulled
Published on 2010-04-07T00:18:30Z Indexed on 2010/04/07 0:23 UTC
Read the original article Hit count: 593

Filed under:

pointers

|

void-pointers

|

function

|

argument-passing

|

c

Hi,

I can't understand this result...

The code:

void foo(void * key, size_t key_sz) {
    HashItem *item = malloc(sizeof(HashItem));

    printf("[%d]\n", (int)key);

    ...

    item->key = malloc(key_sz);
    memcpy(item->key, key, key_sz);
}

void bar(int num) {
    foo(&num, sizeof(int));
}

And I do this call: bar(900011009);

But the printf() output is:

[-1074593956]

I really need key to be a void pointer, how can I fix this?

© Stack Overflow or respective owner

Related posts about pointers

C++ smart pointers: sharing pointers vs. sharing data

as seen on Stack Overflow - Search for 'Stack Overflow'
In this insightful article, one of the Qt programmers tries to explain the different kinds of smart pointers Qt implements. In the beginning, he makes a distinction between sharing data and sharing the pointers themselves: First, let’s get one thing straight: there’s a difference between sharing … >>> More
handling refrence to pointers/double pointers using SWIG [C++ to Java]

as seen on Stack Overflow - Search for 'Stack Overflow'
My code has an interface like class IExample { ~IExample(); //pure virtual methods ...}; a class inheriting the interface like class CExample : public IExample { protected: CExample(); //implementation of pure virtual methods ... }; and a global function to create object of this class - createExample(… >>> More
char pointers & integer pointers (++)

as seen on Stack Overflow - Search for 'Stack Overflow'
i have two pointers, char *str1; int *str2; if i look at the size of both the pointers lets assume str1=4 bytes str2=4 bytes str1++ will increment by 1 byte but if str2++ will increment 4 byte could anybody tell e the concept behind this? >>> More
Smart pointers - cases where they cannot replace raw pointers

as seen on Stack Overflow - Search for 'Stack Overflow'
HI, I have this query about smart pointers. I heard from one of my friends that smart pointers can almost always replace raw pointers. but when i asked him what are the other cases where smart pointers cannot replace the raw pointers,i did not get the answer from him. could anybody please tell… >>> More
C++ Pointers: Number of levels of Indirection

as seen on Programmers - Search for 'Programmers'
In a C++ program that doesn't contain legacy C code, is there a guideline regarding the maximum number of levels of indirection that should be used in the source code? I know that in C (as opposed to C++), some programmers have used pointers to pointers for a multiple dimension array, but for the… >>> More

Related posts about void-pointers

How to get rid of void-pointers.

as seen on Stack Overflow - Search for 'Stack Overflow'
I inherited a big application that was originally written in C (but in the mean time a lot of C++ was also added to it). Because of historical reasons, the application contains a lot of void-pointers. Before you start to choke, let me explain why this was done. The application contains many different… >>> More
Void pointers in C

as seen on Stack Overflow - Search for 'Stack Overflow'
I have written this qsort: void qsort(void *a[],int low,int high, int (*compare)(void*,void*)); When I call this on char *strarr[5]; It says invalid conversion from char** to void**. Why this is wrong? This is the code:http://codepad.org/Flfm2zAE >>> More
What are void pointers for in C++?

as seen on Stack Overflow - Search for 'Stack Overflow'
My question is simple: What are void pointers for in C++? (Those things you declare with void* myptr;) What is their use? Can I make them point to a variable of any type? >>> More
C++: How to build an events / messaging system without void pointers?

as seen on Stack Overflow - Search for 'Stack Overflow'
I'd like to have a dynamic messaging system in my C++ project, one where there is a fixed list of existing events, events can be triggered anywhere during runtime, and where you can subscribe callback functions to certain events. There should be an option for arguments passed around in those events… >>> More
Issue with dynamic array Queue data structure with void pointer

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, Maybe there's no way to solve this the way I'd like it but I don't know everything so I better ask... I've implemented a simple Queue with a dynamic array so the user can initialize with whatever number of items it wants. I'm also trying to use a void pointer as to allow any data type, but that's… >>> More