Free a pointer

Hi all!
I am an new bie!
I have an error, could you should why it wrong and how to fix it!
My sample code:

Code:

---


typedef struct _pointer_note{
        char name[10];
        char *loai;
        int  data;
        float *stack_next;
}pointer;

int main()
{
 pointer p1; //declare a  pointer type variable
 p1.loai = (char*)malloc(sizeof(char)*256);//
 strcpy(p1.loai,"hello world");
 // Do some thing
free(p1.loai);//free a pointer
return 0;
}

---

When run program, an error "DAMAGE: after normal block(#42)"

Help me!
Thanks!

So how much code have you commented out with the "// do some thing" ?

Quote:

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Originally Posted by Salem

So how much code have you commented out with the "// do some thing" ?

---

I do not add anything at this. My code really like this

Code:

---

pointer p1; //declare a  pointer type variable
 p1.loai = (char*)malloc(sizeof(char)*256);//
 strcpy(p1.loai,"hello world");
 free(p1.loai);//free a pointer

---

Thanks!

I've no idea why that program would cause that to happen. It looks OK and works as expected here.

The message you get suggests that you overwrote some memory, for example copying more than 10 characters to the name.

Are you just compiling the program, or are you doing something like "rebuild all".
Just occasionally, doing a "rebuild all" fixes things.

Check if you included stdlib.h

remove the (char *) cast from malloc and see if your compiler warns you that there is no prototype for malloc.

On what platform do you work?

Thanks Salem!
I think error in complie envoriment, because when I write a sample program and complie in Turbo C 3.0, it run well but when I complie in VC++ 6.0, it appear this error!

nemo3110, Seriously get with the times. Turbo C 3.0 was released in 1991, That's at least 17 years.

Works for me in VC6.

Besides, if it really is bug-free then it should work with all compilers, not just a selection.

Are you absolutely sure you're pasting the code you're running, and not just writing it out again from memory based on what you think you wrote (we get that a lot here).

Because if you really have
strcpy(p1.name,"hello world");
and not as you claim
strcpy(p1.loai,"hello world");
then I can easily believe that you'd get the message you're seeing.

More specifically, I also get "Damage after..." when I change the 256 to be something less than the length of the "hello world" string, say just 10 bytes.

did you try my suggestion? removing the (char *) cast from malloc