c - C 中的堆分配

Question

据我了解，您可以使用相同的变量名重新分配一个堆，它会在空间的不同位置分配内存。

但是，在这个例子中，我在我的第二个 malloc 中为指针变量 x 获得了相同的内存地址。有什么想法吗？

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 给我这个:

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

Answer 1

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

&x 这里它给出了变量 x 的地址，而不是它指向的内容。要获取它指向的地址，请使用以下内容:

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