void pointer dereferencing

Question

Possible Duplicate:
Dereferencing void pointers

I have a function call this way:

void foo(void *context)   //function prototype
..
..
..
main()
{
.
.
foo(&(ptr->block));  //where ptr->block is of type integer.
.
.
.
void foo(void *context)
{
 Here I try to use the ptr->block but am having problems. I have tried 

 if((int *)context ==1)  
  ..
  ..
}

I am typecasting it back to int in the function to use it. Am I dereferencing it wrong inside the foo() function?

score 5 · Accepted Answer · answered Dec 29 '12 at 01:33

5

if((int *)context ==1)

you want this instead:

if(*(int *)context ==1)

You were casting to a pointer to int but what you actually want is to actually access the int so you need to dereference the pointer.

answered Dec 29 '12 at 01:33

ouah

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score 3 · Answer 2 · answered Dec 29 '12 at 01:33

3

You didn't typecast it to int, you typecast it to int *, and then didn't dereference it. Try:

if (*(int *)context == 1)

answered Dec 29 '12 at 01:33

Carl Norum

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Thanks for the instant reply! SO folks are just too good :-) – mane Dec 29 '12 at 01:39

score 0 · Answer 3 · answered Dec 29 '12 at 03:08

0

when you want to access the value, just casting the pointer wont help you..

(*(int*)context == 1) will solve your issue..

answered Dec 29 '12 at 03:08

Raghu Srikanth Reddy

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void pointer dereferencing

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