CODEWITHSUNDEEP
cdynamicmallocheap-memory
spaul
spaul

Reputation: 13

Heap Allocation in C

It is my understanding that you can reallocate a heap using the same variable name and it will allocate memory in a different location in space.

However, in this example, I am getting the same memory address in my second malloc for the pointer variable x. Any ideas?

void main()
{
    int *x = (int*)malloc(sizeof(int)); //allocate space for int value
    *x = 100;   //dereference x for value
    printf("The value of x is %i address is %p\n",*x, &x);

    int *y = (int*)malloc(sizeof(int)); //allocate space for int value
    *y = 150;   //dereference x for value
    printf("The value of y is %i address is %p\n",*y, &y); 

    x = (int*)malloc(sizeof(int));  //allocate space for int value
    *x = 400;   //dereference x for value
    printf("The value of x is %i address is %p\n",*x, &x);
}

gcc gives me this:

The value of x is 100 address is 0xffffcc08
The value of y is 150 address is 0xffffcc00
The value of x is 400 address is 0xffffcc08

Upvotes: 0

Views: 431

Answers (1)

Rizwan
Rizwan

Reputation: 3696

printf("The value of x is %i address is %p\n",*x, &x);

&x here it gives the address of the variable x and not what it is pointing to. To get the address of where it is pointing to use following :

printf("The value of x is %i address is %p\n",*x, (void *)x)

Upvotes: 3

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