Dangling pointer example confusion

Question

Why isn't the following example correct? Why doesn't it demonstrate a dangling pointer? My teacher said it doesn't show the dangling pointer. Thanks in advance!

int X = 32;
int *p = &X;
free(p);
*p = 32; //<------Shouldn't this line cause dangling pointer ???

Same thing here. Why doesn't the following example demonstrate a memory leak?

void function(int x){
   int *p = &x;
   *p = 32;
   //shouln't this code show a warning as p was not freed?
}

Answer 1

To cite Wikipedia:

Dangling pointer and wild pointers in computer programming are pointers that do not point to a valid object of the appropriate type.

Also you should only free memory which was allocated by malloc or similar allocation functions -it seems that is your confusion in both cases. Basically none of your examples need free.

An example of dangling pointer would be:

{
   char *ptr = NULL;

   {
       char c;
       ptr = &c;
   } 
     // c falls out of scope 
     // ptr is now a dangling pointer 
}

Also if you had example like:

int *p = malloc(sizeof(int));
*p = 9;
free(p); // now p is dangling