still available even after freeing dynamic allocated memory

[perlsu]

I would like to know whether the dynamic memory pointer is still available even after freeing the allocated memory. If I want to allocate and deallocate so many times within a loop , I receive memory corruption. Pls help me how I should do.If I call "free" more than one time, it reports error because allocated memory is already freed even though there is still available. I don't understand this concept . Pls help me.The program is as follows.

Best Rgds,
perlsu

#include #include #include void main() { int i = 0; unsigned char* temp = NULL; unsigned char st[] = "Hello";

for ( i = 0;i < 10;i++) { temp = (unsigned char*) malloc( strlen(st) ); memcpy( temp, st, strlen(st));

if (temp) free(temp);

if (temp) printf("still available"); else printf("already destroyed"); if (temp) free(temp);

} }

[Bench]

when you "free" memory, you are deleting the object which "temp" points to, you are not modifying temp itself. What you are left with is a dangling pointer which points to some undefined part of memory, which could contain absolutely anything. you should assign the value of NULL to "temp" after freeing the memory.

[Narue]

>I would like to know whether the dynamic memory pointer is still
>available even after freeing the allocated memory.
No, it's not. When you free memory, you must reassign the pointer to memory that you own before you can dereference it again.