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cvariablespointersmemory-address

print the memory location of a variable (or pointer)

I want to print where a variable is stored. I Google it and I found this:

int *p;
printf("memory location of ptr: %p\n",  (void *)p);

If I write this, is it right?

printf("memory location of ptr: %p\n",  &p);

I compiled it and I didn't get any errors or warnings. However, the above two commands didn’t return the same value!

Solution

  • Lets say you have these declarations:

    int i;
int *p = &i;

    It would look something like this in memory:

    +---+     +---+
| p | --> | i |
+---+     +---+

    If you then use &p you get a pointer to p, so you have this:

    +----+     +---+     +---+
| &p | --> | p | --> | i |
+----+     +---+     +---+

    So the value of p is the address of i, and the value of &p is the address of p. That's why you get different values.